I seem to be having a big problem with this over the past year or so. I think there needs to be a rule that leaders of co-ops should not be allowed to send invites to other players who are already in a co-op and the only way a player should be allowed to get an invite is if they are not in any co-ops already! This is becoming extremely annoying to me. This is a game and a game should not be source of frustration like this. To me, this is a major problem right now.