Preform AV alliance or universal
 

Somebody made a mod to group join av, horde only. I don't know how lame that sounds to anybody else, but if somebody could make a universal version that would be handy. thanks!

The UI doesn't allow you to directly group join, the API just plain won't allow it. However, you could, in theory, communicate with everyone and have them click the button at the same time. It wouldn't be any better, though, than just getting on vent with everyone and clicking "join BG" all at the same time. There's no real guarantee you would all get in or get to the same place (though there's probably a pretty high chance of success).