diff --git a/libraries/AP_Param/AP_Param.cpp b/libraries/AP_Param/AP_Param.cpp
index 3e45763931..2eb0da80df 100644
--- a/libraries/AP_Param/AP_Param.cpp
+++ b/libraries/AP_Param/AP_Param.cpp
@@ -1657,6 +1657,35 @@ void AP_Param::convert_old_parameters(const struct ConversionInfo *conversion_ta
     }
 }
 
+/*
+  move old class variables for a class that was sub-classed to one that isn't
+  For example, used when the AP_MotorsTri class changed from having its own parameter table
+  plus a subgroup for AP_MotorsMulticopter to just inheriting the AP_MotorsMulticopter var_info
+
+  This does not handle nesting beyond the single level shift
+*/
+void AP_Param::convert_parent_class(uint8_t param_key, void *object_pointer,
+                                    const struct AP_Param::GroupInfo *group_info)
+{
+    for (uint8_t i=0; group_info[i].type != AP_PARAM_NONE; i++) {
+        struct ConversionInfo info;
+        info.old_key = param_key;
+        info.type = (ap_var_type)group_info[i].type;
+        info.new_name = nullptr;
+        info.old_group_element = uint16_t(group_info[i].idx)<<6;
+        uint8_t old_value[type_size(info.type)];
+        AP_Param *ap = (AP_Param *)&old_value[0];
+        
+        if (!AP_Param::find_old_parameter(&info, ap)) {
+            // the parameter wasn't set in the old eeprom
+            continue;
+        }
+
+        uint8_t *new_value = group_info[i].offset + (uint8_t *)object_pointer;
+        memcpy(new_value, old_value, sizeof(old_value));
+    }
+}
+
 
 /*
   set a parameter to a float value
diff --git a/libraries/AP_Param/AP_Param.h b/libraries/AP_Param/AP_Param.h
index 22033d876f..e5c43a3dc7 100644
--- a/libraries/AP_Param/AP_Param.h
+++ b/libraries/AP_Param/AP_Param.h
@@ -121,7 +121,7 @@ public:
     };
     struct ConversionInfo {
         uint16_t old_key; // k_param_*
-        uint8_t old_group_element; // index in old object
+        uint32_t old_group_element; // index in old object
         enum ap_var_type type; // AP_PARAM_*
         const char *new_name;
     };
@@ -305,6 +305,10 @@ public:
     };
     static void         convert_old_parameter(const struct ConversionInfo *info, float scaler, uint8_t flags=0);
 
+    // move old class variables for a class that was sub-classed to one that isn't
+    static void         convert_parent_class(uint8_t param_key, void *object_pointer,
+                                             const struct AP_Param::GroupInfo *group_info);
+    
     /// Erase all variables in EEPROM.
     ///
     static void         erase_all(void);