How do I create a local multiplayer? (Read Disc.)

I want to make a local multiplayer game(that part is easy). The problem is I want the game to connect like this:

So if a controller connects to player 1, then they will control player one until they disconnect. Is there a way to do this?

Thanks in advance,

TigerKai312

Edit: If someone presses a key(we'll say A), they will be player 1. Then someone else connects, they'll be player 2. And if player 1 disconnects, then player 2 will become player 1.