diff --git a/libraries/AP_Param/AP_Param.cpp b/libraries/AP_Param/AP_Param.cpp
index 0beaeb860a..ff4bd0a00b 100644
--- a/libraries/AP_Param/AP_Param.cpp
+++ b/libraries/AP_Param/AP_Param.cpp
@@ -2087,6 +2087,13 @@ void AP_Param::convert_g2_objects(const void *g2, const G2ObjectConversion g2_co
     }
 }
 
+void AP_Param::convert_toplevel_objects(const TopLevelObjectConversion conversions[], uint8_t num_conversions)
+{
+    for (uint8_t i=0; i<num_conversions; i++) {
+        const auto &c { conversions[i] };
+        convert_class(c.old_index, c.object_pointer, c.var_info, 0, true);
+    }
+}
 
 /*
  convert width of a parameter, allowing update to wider scalar values
diff --git a/libraries/AP_Param/AP_Param.h b/libraries/AP_Param/AP_Param.h
index 1a9284a71e..589fd09fab 100644
--- a/libraries/AP_Param/AP_Param.h
+++ b/libraries/AP_Param/AP_Param.h
@@ -477,10 +477,19 @@ public:
     struct G2ObjectConversion {
         void *object_pointer;
         const struct AP_Param::GroupInfo *var_info;
-        uint16_t old_index;  // Old parameter index in g
+        uint16_t old_index;  // Old parameter index in g2
     };
     static void         convert_g2_objects(const void *g2, const G2ObjectConversion g2_conversions[], uint8_t num_conversions);
 
+    // convert an object which was stored in a vehicle's top-level
+    // Parameters object into a new object in AP_Vehicle.cpp:
+    struct TopLevelObjectConversion {
+        void *object_pointer;
+        const struct AP_Param::GroupInfo *var_info;
+        uint16_t old_index;  // Old parameter index in g
+    };
+    static void         convert_toplevel_objects(const TopLevelObjectConversion g2_conversions[], uint8_t num_conversions);
+
     /*
       convert width of a parameter, allowing update to wider scalar
       values without changing the parameter indexes. This will return