I dont know if this is a bug. I used to short other a/c in the flight of gas. This way I could fly balloon or escort alone or with 1 other a/c. In WOFF UE , I short them down to 20 gals and they fly the entire mission with no problem ?

20 galons is a lot of fuel. Use Mission Editor and you can set any number of pilots or fly alone - Lone Wolf missions.

Yes with mission editor you can begin your flight with the number of aircraft that you want from the start.
Even a lot more interesting options included in this excellent mod.