Creating a Game lobby with socket.io (not using rooms)

I've developed a team-based multiplayer game using socket.io & node.js. I'm using socket.io rooms to implement the teams which is working nicely.

The game is functional and can handle 4+ players. However, I would now like to scale the game to support multiple instances of games and where users can choose to join a specific game from a lobby or create a new game - typical game server/lobby type feature.

I think the normal implementation for this would be to use socket.io rooms but I am already using rooms for the teams within a game so I am a bit stuck with how to scale the game.

via Anup Parekh