diff --git a/include/audacity/ModuleInterface.h b/include/audacity/ModuleInterface.h
index 7f9f62f4b..68f624f59 100644
--- a/include/audacity/ModuleInterface.h
+++ b/include/audacity/ModuleInterface.h
@@ -42,6 +42,14 @@
 #ifndef __AUDACITY_MODULEINTERFACE_H__
 #define __AUDACITY_MODULEINTERFACE_H__
 
+#include <functional>
+
+#ifdef __WXMAC__
+// Needs this for std::function
+// Make this go away when Mac moves to a proper C++11 library
+#include "../../src/MemoryX.h"
+#endif
+
 #include "audacity/Types.h"
 #include "audacity/IdentInterface.h"
 #include "audacity/PluginInterface.h"
@@ -75,23 +83,45 @@ public:
    // Called just prior to deletion to allow releasing any resources.
    virtual void Terminate() = 0;
 
+   // "Paths" returned by FindPluginPaths() and passed back to
+   // DiscoverPluginsAtPath() have module-specific meaning.
+   // They are not necessarily file system paths to existent files that
+   // could be placed in any folder and queried for
+   // plugin information.  This function returns true when that is the case.
+   virtual bool PathsAreFiles() = 0;
+
+   // Returns empty, or else, where to copy a plug-in file or bundle.
+   // Drag-and-drop is supported only if PathsAreFiles() is true and this
+   // function returns nonempty.
+   virtual wxString InstallPath() = 0;
+
    // Modules providing a single or static set of plugins may use
    // AutoRegisterPlugins() to register those plugins.
    virtual bool AutoRegisterPlugins(PluginManagerInterface & pluginManager) = 0;
 
    // For modules providing an interface to other dynamically loaded plugins,
    // the module returns a list of path names that will be presented to the
-   // user for enablement.
-   virtual wxArrayString FindPlugins(PluginManagerInterface & pluginManager) = 0;
+   // user as "New" for enablement.
+   virtual wxArrayString FindPluginPaths(PluginManagerInterface & pluginManager) = 0;
 
-   // Once the user selects desired paths from FindPlugins(), a call to RegisterPlugin()
-   // will be made to request registration of that plugin.  If the module must create
+   // Once the user selects desired paths from FindPluginPaths(),
+   // a call to DiscoverPluginsAtPath()
+   // will be made to request registration of one or more plugins.  If the module must create
    // an instance of the plugin to register it, then then instance should be deleted
    // after registration.
-   // Error message does not need to mention the path.
-   virtual bool RegisterPlugin(PluginManagerInterface & pluginManager,
-                               const wxString & path,
-                               wxString &errMsg) = 0;
+   // May discover more than one plug-in at the path, and
+   // may call-back with paths not equal to path (perhaps appending
+   // other information to it).
+   // Error message does not need to mention the path and may be nonempty
+   // even if some plugins are also discovered successfully.
+   // Return value is the number of plugins found.
+   using RegistrationCallback =
+      std::function< void(ModuleInterface *, EffectIdentInterface *) >;
+   virtual unsigned DiscoverPluginsAtPath(
+      const wxString & path, wxString &errMsg,
+      const RegistrationCallback &callback =
+         PluginManagerInterface::DefaultRegistrationCallback)
+         = 0;
 
    // For modules providing an interface to other dynamically loaded plugins,
    // the module returns true if the plugin is still valid, otherwise false.
diff --git a/include/audacity/PluginInterface.h b/include/audacity/PluginInterface.h
index 489e9959f..9dbd89f38 100644
--- a/include/audacity/PluginInterface.h
+++ b/include/audacity/PluginInterface.h
@@ -54,6 +54,9 @@ class PluginManagerInterface /* not final */
 {
 public:
 
+   static const PluginID &DefaultRegistrationCallback(
+      ModuleInterface *provider, EffectIdentInterface *ident );
+
    virtual bool IsPluginRegistered(const wxString & path) = 0;
 
    virtual const PluginID & RegisterPlugin(ModuleInterface *module) = 0;
diff --git a/src/ModuleManager.cpp b/src/ModuleManager.cpp
index 52e637cca..1db4878e5 100755
--- a/src/ModuleManager.cpp
+++ b/src/ModuleManager.cpp
@@ -514,7 +514,7 @@ void ModuleManager::FindAllPlugins(PluginIDList & providers, wxArrayString & pat
       ModuleInterface *module =
          static_cast<ModuleInterface *>(CreateProviderInstance(providerID, modPaths[i]));
       
-      wxArrayString newpaths = module->FindPlugins(pm);
+      wxArrayString newpaths = module->FindPluginPaths(pm);
       for (size_t i = 0, cnt = newpaths.size(); i < cnt; i++)
       {
          providers.push_back(providerID);
@@ -536,7 +536,7 @@ wxArrayString ModuleManager::FindPluginsForProvider(const PluginID & providerID,
       }
    }
 
-   return mDynModules[providerID]->FindPlugins(PluginManager::Get());
+   return mDynModules[providerID]->FindPluginPaths(PluginManager::Get());
 }
 
 bool ModuleManager::RegisterPlugin(const PluginID & providerID, const wxString & path, wxString &errMsg)
@@ -547,8 +547,9 @@ bool ModuleManager::RegisterPlugin(const PluginID & providerID, const wxString &
       return false;
    }
 
-   return mDynModules[providerID]->RegisterPlugin(PluginManager::Get(), path,
-                                                  errMsg);
+   auto nFound = mDynModules[providerID]->DiscoverPluginsAtPath(path, errMsg);
+
+   return nFound > 0;
 }
 
 IdentInterface *ModuleManager::CreateProviderInstance(const PluginID & providerID,
diff --git a/src/PluginManager.cpp b/src/PluginManager.cpp
index f16dcf9bc..930412531 100644
--- a/src/PluginManager.cpp
+++ b/src/PluginManager.cpp
@@ -1379,6 +1379,12 @@ void PluginDescriptor::SetImporterExtensions(const wxArrayString & extensions)
 //
 // ============================================================================
 
+const PluginID &PluginManagerInterface::DefaultRegistrationCallback(
+   ModuleInterface *provider, EffectIdentInterface *pInterface )
+{
+   return PluginManager::Get().RegisterPlugin(provider, pInterface);
+}
+
 bool PluginManager::IsPluginRegistered(const wxString & path)
 {
    for (PluginMap::iterator iter = mPlugins.begin(); iter != mPlugins.end(); ++iter)
diff --git a/src/effects/LoadEffects.cpp b/src/effects/LoadEffects.cpp
index 41310c5c0..3eae7039e 100644
--- a/src/effects/LoadEffects.cpp
+++ b/src/effects/LoadEffects.cpp
@@ -297,7 +297,8 @@ bool BuiltinEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
       if (!pm.IsPluginRegistered(path))
       {
          // No checking of error ?
-         RegisterPlugin(pm, path, ignoredErrMsg);
+         DiscoverPluginsAtPath(path, ignoredErrMsg,
+            PluginManagerInterface::DefaultRegistrationCallback);
       }
    }
 
@@ -305,25 +306,25 @@ bool BuiltinEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
    return false;
 }
 
-wxArrayString BuiltinEffectsModule::FindPlugins(PluginManagerInterface & WXUNUSED(pm))
+wxArrayString BuiltinEffectsModule::FindPluginPaths(PluginManagerInterface & WXUNUSED(pm))
 {
    return mNames;
 }
 
-bool BuiltinEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
-                                          const wxString & path,
-                                          wxString &errMsg)
+unsigned BuiltinEffectsModule::DiscoverPluginsAtPath(
+   const wxString & path, wxString &errMsg,
+   const RegistrationCallback &callback)
 {
    errMsg.clear();
    auto effect = Instantiate(path);
    if (effect)
    {
-      pm.RegisterPlugin(this, effect.get());
-      return true;
+      callback(this, effect.get());
+      return 1;
    }
 
    errMsg = _("Unknown built-in effect name");
-   return false;
+   return 0;
 }
 
 bool BuiltinEffectsModule::IsPluginValid(const wxString & path, bool bFast)
diff --git a/src/effects/LoadEffects.h b/src/effects/LoadEffects.h
index 9249f51a6..fbf15c4e4 100644
--- a/src/effects/LoadEffects.h
+++ b/src/effects/LoadEffects.h
@@ -41,10 +41,15 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
+   bool PathsAreFiles() override { return false; }
+   wxString InstallPath() override { return {}; }
+
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
-   wxArrayString FindPlugins(PluginManagerInterface & pm) override;
-   bool RegisterPlugin(PluginManagerInterface & pm,
-                       const wxString & path, wxString &errMsg) override;
+   wxArrayString FindPluginPaths(PluginManagerInterface & pm) override;
+   unsigned DiscoverPluginsAtPath(
+      const wxString & path, wxString &errMsg,
+      const RegistrationCallback &callback)
+         override;
 
    bool IsPluginValid(const wxString & path, bool bFast) override;
 
diff --git a/src/effects/VST/VSTEffect.cpp b/src/effects/VST/VSTEffect.cpp
index 60330a359..21b8c44ca 100644
--- a/src/effects/VST/VSTEffect.cpp
+++ b/src/effects/VST/VSTEffect.cpp
@@ -351,13 +351,21 @@ void VSTEffectsModule::Terminate()
    return;
 }
 
+wxString VSTEffectsModule::InstallPath()
+{
+   // Not yet ready for VST drag-and-drop...
+   // return FileNames::PlugInDir();
+
+   return {};
+}
+
 bool VSTEffectsModule::AutoRegisterPlugins(PluginManagerInterface & WXUNUSED(pm))
 {
    // We don't auto-register
    return true;
 }
 
-wxArrayString VSTEffectsModule::FindPlugins(PluginManagerInterface & pm)
+wxArrayString VSTEffectsModule::FindPluginPaths(PluginManagerInterface & pm)
 {
    wxArrayString pathList;
    wxArrayString files;
@@ -466,10 +474,12 @@ wxArrayString VSTEffectsModule::FindPlugins(PluginManagerInterface & pm)
    return files;
 }
 
-bool VSTEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
-                                      const wxString & path, wxString &errMsg)
+unsigned VSTEffectsModule::DiscoverPluginsAtPath(
+   const wxString & path, wxString &errMsg,
+   const RegistrationCallback &callback)
 {
    bool error = false;
+   unsigned nFound = 0;
    errMsg.clear();
    // TODO:  Fix this for external usage
    const wxString &cmdpath = PlatformCompatibility::GetExecutablePath();
@@ -620,7 +630,8 @@ bool VSTEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
                if (!skip && cont)
                {
                   valid = true;
-                  pm.RegisterPlugin(this, &proc);
+                  callback( this, &proc );
+                  ++nFound;
                }
             }
             break;
@@ -636,7 +647,7 @@ bool VSTEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
    if (error)
       errMsg = _("Could not load the library");
 
-   return valid;
+   return nFound;
 }
 
 bool VSTEffectsModule::IsPluginValid(const wxString & path, bool bFast)
diff --git a/src/effects/VST/VSTEffect.h b/src/effects/VST/VSTEffect.h
index 4ecaee64d..9de346fbf 100644
--- a/src/effects/VST/VSTEffect.h
+++ b/src/effects/VST/VSTEffect.h
@@ -391,10 +391,15 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
+   bool PathsAreFiles() override { return true; }
+   wxString InstallPath() override;
+
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
-   wxArrayString FindPlugins(PluginManagerInterface & pm) override;
-   bool RegisterPlugin(PluginManagerInterface & pm,
-                       const wxString & path, wxString &errMsg) override;
+   wxArrayString FindPluginPaths(PluginManagerInterface & pm) override;
+   unsigned DiscoverPluginsAtPath(
+      const wxString & path, wxString &errMsg,
+      const RegistrationCallback &callback)
+         override;
 
    bool IsPluginValid(const wxString & path, bool bFast) override;
 
diff --git a/src/effects/audiounits/AudioUnitEffect.cpp b/src/effects/audiounits/AudioUnitEffect.cpp
index e7424f04f..00c499067 100644
--- a/src/effects/audiounits/AudioUnitEffect.cpp
+++ b/src/effects/audiounits/AudioUnitEffect.cpp
@@ -158,7 +158,7 @@ bool AudioUnitEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
    return true;
 }
 
-wxArrayString AudioUnitEffectsModule::FindPlugins(PluginManagerInterface & pm)
+wxArrayString AudioUnitEffectsModule::FindPluginPaths(PluginManagerInterface & pm)
 {
    wxArrayString effects;
 
@@ -171,9 +171,9 @@ wxArrayString AudioUnitEffectsModule::FindPlugins(PluginManagerInterface & pm)
    return effects;
 }
 
-bool AudioUnitEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
-                                            const wxString & path,
-                                            wxString &errMsg)
+unsigned AudioUnitEffectsModule::DiscoverPluginsAtPath(
+   const wxString & path, wxString &errMsg,
+   const RegistrationCallback &callback)
 {
    errMsg.clear();
    wxString name;
@@ -181,7 +181,7 @@ bool AudioUnitEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
    if (component == NULL)
    {
       errMsg = _("Could not find component");
-      return false;
+      return 0;
    }
 
    AudioUnitEffect effect(path, name, component);
@@ -190,12 +190,11 @@ bool AudioUnitEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
       // TODO:  Is it worth it to discriminate all the ways SetHost might
       // return false?
       errMsg = _("Could not initialize component");
-      return false;
+      return 0;
    }
 
-   pm.RegisterPlugin(this, &effect);
-
-   return true;
+   callback(this, &effect);
+   return 1;
 }
 
 bool AudioUnitEffectsModule::IsPluginValid(
diff --git a/src/effects/audiounits/AudioUnitEffect.h b/src/effects/audiounits/AudioUnitEffect.h
index b49a348d9..3b5c001b1 100644
--- a/src/effects/audiounits/AudioUnitEffect.h
+++ b/src/effects/audiounits/AudioUnitEffect.h
@@ -243,10 +243,15 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
+   bool PathsAreFiles() override { return false; }
+   wxString InstallPath() override { return {}; }
+
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
-   wxArrayString FindPlugins(PluginManagerInterface & pm) override;
-   bool RegisterPlugin(PluginManagerInterface & pm,
-                       const wxString & path, wxString &errMsg) override;
+   wxArrayString FindPluginPaths(PluginManagerInterface & pm) override;
+   unsigned DiscoverPluginsAtPath(
+      const wxString & path, wxString &errMsg,
+      const RegistrationCallback &callback)
+         override;
 
    bool IsPluginValid(const wxString & path, bool bFast) override;
 
diff --git a/src/effects/ladspa/LadspaEffect.cpp b/src/effects/ladspa/LadspaEffect.cpp
index 2852c7bee..5aed54616 100644
--- a/src/effects/ladspa/LadspaEffect.cpp
+++ b/src/effects/ladspa/LadspaEffect.cpp
@@ -49,6 +49,7 @@ effects from this one class.
 #include <wx/version.h>
 
 #include "LadspaEffect.h"       // This class's header file
+#include "../../FileNames.h"
 #include "../../Internat.h"
 #include "../../ShuttleGui.h"
 #include "../../widgets/valnum.h"
@@ -154,6 +155,12 @@ void LadspaEffectsModule::Terminate()
    return;
 }
 
+wxString LadspaEffectsModule::InstallPath()
+{
+   // To do: better choice
+   return FileNames::PlugInDir();
+}
+
 bool LadspaEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
 {
    // Autoregister effects that we "think" are ones that have been shipped with
@@ -171,7 +178,8 @@ bool LadspaEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
          if (!pm.IsPluginRegistered(files[j]))
          {
             // No checking for error ?
-            RegisterPlugin(pm, files[j], ignoredErrMsg);
+            DiscoverPluginsAtPath(files[j], ignoredErrMsg,
+               PluginManagerInterface::DefaultRegistrationCallback);
          }
       }
    }
@@ -180,7 +188,7 @@ bool LadspaEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
    return false;
 }
 
-wxArrayString LadspaEffectsModule::FindPlugins(PluginManagerInterface & pm)
+wxArrayString LadspaEffectsModule::FindPluginPaths(PluginManagerInterface & pm)
 {
    wxArrayString pathList = GetSearchPaths();
    wxArrayString files;
@@ -205,9 +213,9 @@ wxArrayString LadspaEffectsModule::FindPlugins(PluginManagerInterface & pm)
    return files;
 }
 
-bool LadspaEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
-                                         const wxString & path,
-                                         wxString &errMsg)
+unsigned LadspaEffectsModule::DiscoverPluginsAtPath(
+   const wxString & path, wxString &errMsg,
+   const RegistrationCallback &callback)
 {
    errMsg.clear();
    // Since we now have builtin VST support, ignore the VST bridge as it
@@ -215,7 +223,7 @@ bool LadspaEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
    wxFileName ff(path);
    if (ff.GetName().CmpNoCase(wxT("vst-bridge")) == 0) {
       errMsg = _("Audacity no longer uses vst-bridge");
-      return false;
+      return 0;
    }
 
    // As a courtesy to some plug-ins that might be bridges to
@@ -227,8 +235,8 @@ bool LadspaEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
    wxString saveOldCWD = ff.GetCwd();
    ff.SetCwd();
 
-   bool error = false;
    int index = 0;
+   int nLoaded = 0;
    LADSPA_Descriptor_Function mainFn = NULL;
    wxDynamicLibrary lib;
    if (lib.Load(path, wxDL_NOW)) {
@@ -241,15 +249,16 @@ bool LadspaEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
          for (data = mainFn(index); data; data = mainFn(++index)) {
             LadspaEffect effect(path, index);
             if (effect.SetHost(NULL)) {
-               pm.RegisterPlugin(this, &effect);
-            }
-            else {
-               // If pm.RegisterPlugin is skipped, be sure to report error
-               error = true;
+               ++nLoaded;
+               callback( this, &effect );
             }
+            else
+               errMsg = _("Could not load the library");
          }
       }
    }
+   else
+      errMsg = _("Could not load the library");
 
    if (lib.IsLoaded()) {
       // PRL:  I suspect Bug1257 -- Crash when enabling Amplio2 -- is the fault of a timing-
@@ -263,10 +272,7 @@ bool LadspaEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
    wxSetWorkingDirectory(saveOldCWD);
    hadpath ? wxSetEnv(wxT("PATH"), envpath) : wxUnsetEnv(wxT("PATH"));
 
-   if (error)
-      errMsg = _("Could not load the library");
-
-   return index > 0;
+   return nLoaded;
 }
 
 bool LadspaEffectsModule::IsPluginValid(const wxString & path, bool bFast)
diff --git a/src/effects/ladspa/LadspaEffect.h b/src/effects/ladspa/LadspaEffect.h
index 602da74e1..8e4918e10 100644
--- a/src/effects/ladspa/LadspaEffect.h
+++ b/src/effects/ladspa/LadspaEffect.h
@@ -223,10 +223,15 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
+   bool PathsAreFiles() override { return true; }
+   wxString InstallPath() override;
+
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
-   wxArrayString FindPlugins(PluginManagerInterface & pm) override;
-   bool RegisterPlugin(PluginManagerInterface & pm, const wxString & path,
-                       wxString &errMsg) override;
+   wxArrayString FindPluginPaths(PluginManagerInterface & pm) override;
+   unsigned DiscoverPluginsAtPath(
+      const wxString & path, wxString &errMsg,
+      const RegistrationCallback &callback)
+         override;
 
    bool IsPluginValid(const wxString & path, bool bFast) override;
 
diff --git a/src/effects/lv2/LoadLV2.cpp b/src/effects/lv2/LoadLV2.cpp
index f479be3b3..8f12a3cea 100644
--- a/src/effects/lv2/LoadLV2.cpp
+++ b/src/effects/lv2/LoadLV2.cpp
@@ -218,7 +218,7 @@ bool LV2EffectsModule::AutoRegisterPlugins(PluginManagerInterface & WXUNUSED(pm)
    return false;
 }
 
-wxArrayString LV2EffectsModule::FindPlugins(PluginManagerInterface & WXUNUSED(pm))
+wxArrayString LV2EffectsModule::FindPluginPaths(PluginManagerInterface & WXUNUSED(pm))
 {
    // Retrieve data about all LV2 plugins
    const LilvPlugins *plugs = lilv_world_get_all_plugins(gWorld);
@@ -242,8 +242,9 @@ wxArrayString LV2EffectsModule::FindPlugins(PluginManagerInterface & WXUNUSED(pm
    return plugins;
 }
 
-bool LV2EffectsModule::RegisterPlugin(PluginManagerInterface & pm,
-                                      const wxString & path, wxString &errMsg)
+unsigned LV2EffectsModule::DiscoverPluginsAtPath(
+   const wxString & path, wxString &errMsg,
+   const RegistrationCallback &callback)
 {
    errMsg.clear();
    const LilvPlugin *plug = GetPlugin(path);
@@ -252,13 +253,13 @@ bool LV2EffectsModule::RegisterPlugin(PluginManagerInterface & pm,
       LV2Effect effect(plug);
       if (effect.SetHost(NULL))
       {
-         pm.RegisterPlugin(this, &effect);
-         return true;
+         callback( this, &effect );
+         return 1;
       }
    }
 
    errMsg = _("Could not load the library");
-   return false;
+   return 0;
 }
 
 bool LV2EffectsModule::IsPluginValid(const wxString & path, bool bFast)
diff --git a/src/effects/lv2/LoadLV2.h b/src/effects/lv2/LoadLV2.h
index ea9da07dd..b89bdab1a 100644
--- a/src/effects/lv2/LoadLV2.h
+++ b/src/effects/lv2/LoadLV2.h
@@ -88,10 +88,15 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
+   bool PathsAreFiles() override { return false; }
+   wxString InstallPath() override { return {}; }
+
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
-   wxArrayString FindPlugins(PluginManagerInterface & pm) override;
-   bool RegisterPlugin(PluginManagerInterface & pm,
-                       const wxString & path, wxString &errMsg) override;
+   wxArrayString FindPluginPaths(PluginManagerInterface & pm) override;
+   unsigned DiscoverPluginsAtPath(
+      const wxString & path, wxString &errMsg,
+      const RegistrationCallback &callback)
+         override;
 
    bool IsPluginValid(const wxString & path, bool bFast) override;
 
diff --git a/src/effects/nyquist/LoadNyquist.cpp b/src/effects/nyquist/LoadNyquist.cpp
index 00e6ca5aa..c60226f18 100644
--- a/src/effects/nyquist/LoadNyquist.cpp
+++ b/src/effects/nyquist/LoadNyquist.cpp
@@ -15,6 +15,7 @@
 #include "Nyquist.h"
 
 #include "LoadNyquist.h"
+#include "../../FileNames.h"
 
 // ============================================================================
 // List of effects that ship with Audacity.  These will be autoregistered.
@@ -159,6 +160,11 @@ void NyquistEffectsModule::Terminate()
    return;
 }
 
+wxString NyquistEffectsModule::InstallPath()
+{
+   return FileNames::PlugInDir();
+}
+
 bool NyquistEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
 {
    // Autoregister effects that we "think" are ones that have been shipped with
@@ -170,7 +176,8 @@ bool NyquistEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
    if (!pm.IsPluginRegistered(NYQUIST_PROMPT_ID))
    {
       // No checking of error ?
-      RegisterPlugin(pm, NYQUIST_PROMPT_ID, ignoredErrMsg);
+      DiscoverPluginsAtPath(NYQUIST_PROMPT_ID, ignoredErrMsg,
+         PluginManagerInterface::DefaultRegistrationCallback);
    }
 
    for (size_t i = 0; i < WXSIZEOF(kShippedEffects); i++)
@@ -182,7 +189,8 @@ bool NyquistEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
          if (!pm.IsPluginRegistered(files[j]))
          {
             // No checking of error ?
-            RegisterPlugin(pm, files[j], ignoredErrMsg);
+            DiscoverPluginsAtPath(files[j], ignoredErrMsg,
+               PluginManagerInterface::DefaultRegistrationCallback);
          }
       }
    }
@@ -191,7 +199,7 @@ bool NyquistEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
    return false;
 }
 
-wxArrayString NyquistEffectsModule::FindPlugins(PluginManagerInterface & pm)
+wxArrayString NyquistEffectsModule::FindPluginPaths(PluginManagerInterface & pm)
 {
    wxArrayString pathList = NyquistEffect::GetNyquistSearchPath();
    wxArrayString files;
@@ -207,20 +215,20 @@ wxArrayString NyquistEffectsModule::FindPlugins(PluginManagerInterface & pm)
    return files;
 }
 
-bool NyquistEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
-                                          const wxString & path,
-                                          wxString &errMsg)
+unsigned NyquistEffectsModule::DiscoverPluginsAtPath(
+   const wxString & path, wxString &errMsg,
+   const RegistrationCallback &callback)
 {
    errMsg.clear();
    NyquistEffect effect(path);
    if (effect.IsOk())
    {
-      pm.RegisterPlugin(this, &effect);
-      return true;
+      callback(this, &effect);
+      return 1;
    }
 
    errMsg = effect.InitializationError();
-   return false;
+   return 0;
 }
 
 bool NyquistEffectsModule::IsPluginValid(const wxString & path, bool bFast)
diff --git a/src/effects/nyquist/LoadNyquist.h b/src/effects/nyquist/LoadNyquist.h
index 81da38c1b..5d208bacb 100644
--- a/src/effects/nyquist/LoadNyquist.h
+++ b/src/effects/nyquist/LoadNyquist.h
@@ -38,10 +38,15 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
+   bool PathsAreFiles() override { return true; }
+   wxString InstallPath() override;
+
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
-   wxArrayString FindPlugins(PluginManagerInterface & pm) override;
-   bool RegisterPlugin(PluginManagerInterface & pm,
-                       const wxString & path, wxString &errMsg) override;
+   wxArrayString FindPluginPaths(PluginManagerInterface & pm) override;
+   unsigned DiscoverPluginsAtPath(
+      const wxString & path, wxString &errMsg,
+      const RegistrationCallback &callback)
+         override;
 
    bool IsPluginValid(const wxString & path, bool bFast) override;
 
diff --git a/src/effects/vamp/LoadVamp.cpp b/src/effects/vamp/LoadVamp.cpp
index 12fe5f7bc..6e2ed2058 100644
--- a/src/effects/vamp/LoadVamp.cpp
+++ b/src/effects/vamp/LoadVamp.cpp
@@ -122,7 +122,7 @@ bool VampEffectsModule::AutoRegisterPlugins(PluginManagerInterface & WXUNUSED(pm
    return false;
 }
 
-wxArrayString VampEffectsModule::FindPlugins(PluginManagerInterface & WXUNUSED(pm))
+wxArrayString VampEffectsModule::FindPluginPaths(PluginManagerInterface & WXUNUSED(pm))
 {
    wxArrayString names;
 
@@ -199,8 +199,9 @@ wxArrayString VampEffectsModule::FindPlugins(PluginManagerInterface & WXUNUSED(p
    return names;
 }
 
-bool VampEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
-                                       const wxString & path, wxString &errMsg)
+unsigned VampEffectsModule::DiscoverPluginsAtPath(
+   const wxString & path, wxString &errMsg,
+   const RegistrationCallback &callback)
 {
    errMsg.clear();
    int output;
@@ -210,13 +211,13 @@ bool VampEffectsModule::RegisterPlugin(PluginManagerInterface & pm,
    if (vp)
    {
       VampEffect effect(std::move(vp), path, output, hasParameters);
-      pm.RegisterPlugin(this, &effect);
+      callback( this, &effect );
 
-      return true;
+      return 1;
    }
 
    errMsg = _("Could not load the library");
-   return false;
+   return 0;
 }
 
 bool VampEffectsModule::IsPluginValid(const wxString & path, bool bFast)
diff --git a/src/effects/vamp/LoadVamp.h b/src/effects/vamp/LoadVamp.h
index f24fd8fe5..f7025751c 100644
--- a/src/effects/vamp/LoadVamp.h
+++ b/src/effects/vamp/LoadVamp.h
@@ -42,10 +42,15 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
+   bool PathsAreFiles() override { return false; }
+   wxString InstallPath() override { return {}; }
+
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
-   wxArrayString FindPlugins(PluginManagerInterface & pm) override;
-   bool RegisterPlugin(PluginManagerInterface & pm,
-                       const wxString & path, wxString &errMsg) override;
+   wxArrayString FindPluginPaths(PluginManagerInterface & pm) override;
+   unsigned DiscoverPluginsAtPath(
+      const wxString & path, wxString &errMsg,
+      const RegistrationCallback &callback)
+         override;
 
    bool IsPluginValid(const wxString & path, bool bFast) override;