What I would do:
Create a server-client environment.
- Server -> Start server
- Client -> Start client
- Client -> Join server
- Server -> Jibber jabber game state/level
- Server -> Send send message CreatePlayer(ID)
- Server -> (optinally) Sends all other player ID's
- Client -> Creates player with ID
- Client -> Send player update info to server
- Server -> Send client player update to the other clients

This way both server and client know the status and ID of the player. And as you can see the server is the master that know everything. He knows when a player connects or disconnects, so he can also notify the other clients.