I think by default any asset as vanilla passenger plane will be able to be spawned as medium passenger plane in the airport DLC. To specifically make it as small passenger plane, the asset creator have to specifically make it in that way. Also all my fighter jets are saved as cargo plane or light aircraft, none of them are used as passenger plane in game.

This one is used as the light aircraft in the sunset harbor aviation club, not the passenger plane.

how would you set this as a small passenger plane for the airports DLC? having issues to get these to spawn as they only spawn on the vanilla airports.