Aaaaaha! Now I got it!
You want to have pre-defined planes which the players who join in can select and fly (like the IL2 Coop). Not that everybody can join the server and select whatever plane he may wish.
Otherwise the bombing mission of 4 Ju-87 and 4 Bf109 cover can become a 8 Bf109 strafing party
Hmmm...good point I do not know how this is handled in today's server.
Ataros?