I know I’ve seen previous discussion on how to get the sim to more reliably/realistically populate parking ramps with appropriate aircraft.
Every small strip I arrive at is populated with nothing but Sonex JSX-2s. That was amusing at first, but I’m tired of it. Anyone remember the fix?
I believe that the Sonex Aircraft is a marketplace product.
If you do not want this aircraft parked, do the following as mentioned by @TheSevenflyer
Go to the aircraft.cfg for the balloon, and ensure this line reads 0 as below,
or add the line if it isn’t there.
isAirTraffic = 0 ; Is the plane usable for air traffic
Thread Link: How to Stop Add-on Aircraft Showing as Parked Traffic At Airports?
That will help get rid of the Sonex at airports. I cannot, however, answer your question on how to have different aircraft shown at airports.
Hope this helps!