How can I get a camera to move in relation to 2 players on one screen?

I am making a sidescroller where when the back button is pressed a 2nd player will come in via create player. I have been asked to change the format from the default splitscreen to a shared camera that will zoom out if players move too far away from each other and will follow both of them as they progress. How can I do this? Preferably with blueprints.

Also a side bonus question:
Currently the 2nd player comes in when the back button is pressed on controller 1, but we want it to occur on controller 2. Is there a way we can check for a 2nd controller plugged in and read inputs from that? For what its worth we are using 360 controllers.

Thanks

You need to take the two objects and compute a bounding sphere that encapsulates both objects, then you need to find the distance that fits your particular camera to that sphere. Then you just place the camera that far back.

Math here: http://stackoverflow.com/questions/2866350/move-camera-to-fit-3d-scene

Cheers,
Nick