I'm not sure if English is your primary language, but if I understand you correctly then simply playing in invitation only games, or utilizing invites should cover this. Although I wouldn't oppose limiting players in a game, or expanding them.
Forgive me if I am not in the correct sub forum, but I am drawing up short on my season achievement which would unlock a stash space. I need to finish one more conquest but I seem to keep coming up short.
I'd be willing take any reasonable advice and or welcome any help I can get!