to delete an object just click on it then hit the delete key on your keyboard, its as simple as that but if you delete the group leader befor unattaching the others in the group then they all go away so keep that in mind.
as to the rest, i havent done anything with mission editor in ages but i think there was always issues getting planes to fly in groups. its like the game doesnt want more then just a few planes at a time but im sure theres a way to figure it out. i never had the patience but maybe forget the groups and set then up as all seperate planes might allow a large group to fly but just keep trying things till you get something your happy with and when your done please post it for downloading so we can enjoy it too
