OK, got that but still can't quite figure this out. You see, I'm trying to switch the stock 109E to a 3rd party 109E-7. They go with the same name; all you had to do was to add the panel and the sounds of the the stock plane to the new one to make it run, which it did, in Freeflight and Quickcombat. But their .dp files are identical with sim=Bf 109e string, so just changing the id doesn't work.
Nevermind- got it

Just took some more renaming and tweaking.
Now we're talking: 2x13mm + 2x7.92 +1x20mm plus better maneuverability. Still no match to Hurricanes and Spitfires in a turn fight but at least it won't stall so damn easily anymore (Ace/100%)