I agree with Hakaku. However if we do have a new biller, try creating "chat owners" where they could invite, add, and whatever people to a chat. Like Hakaku said, if a user still has authority in a zone, and they have never removed the user even after a long time of inactivity, they are compromising their own security. And as Samapico said, a limit to usernames should be instated. I would not do IP but rather do email because there are siblings, roommates, etc. that sometimes play aswell. Still a limit should be put forth.