last time i check if you try to make an Addon/Plugin similar to the ns430 and add it to an existing Plane, DCS throws this error
Scripting: plugin: test_addon unit modification F-5E not allowed
it works perfectly fine with a UserMade Plane (like CubanAces su57 for example)
if there has been a change to that, that would be great news
(and yes the test_addon was in the SavedGames folder as other Mods)