Shoutbox

You could still kinda do it, something like:

• When a new convo opens, hide it.
  
• If its a one-person convo, show it, finished.
  
• If theres 3+ people then ask if you want to enter the convo
  
• If yes, show the convo, if no, close the convo.

Seems too simple to me, so there must be a flaw in it