Pixel Streaming Scalability

Hello, I have managed deploying my pixel streaming game, and successfully create multiuser experience with matchmaker server by altering the parameters in the exe with adding parameter --matchmakerPort=9999 in exe 1, matchmakerPort=9988 in exe 2, matchmakerPort=9977 in exe 3.

Run exe 1 and let player enter, the player will be redirected to port 9999 and control the first instance
Run exe 2 and let player enter, the player will be redirected to port 9988 and control the second instance, etc…

But I don’t know yet how to automate so first player will enter 9999, second will enter 9988, but when the first player logged out, port 9999 will be empty, so the third player when entering will use port 9999

Where would I set that up?