A gui to select the player controlled object?

Greetings all.

In an effort to get some light scripting experience under my belt, Im working on a simple top down combat game. Currently in my editor scene, I have 4 little soldiers sprites named PlayerA, PlayerB, PlayerC, and PlayerD. They are all behavior-based (no datablocks or anything) and are set up to shoot different projectiles and move at different speeds. I also have a "Select Your Player" gui that I can pop open with a button for each solider option embedded in it. I'm now at a loss as to how to effectively connect the gui with the different player objects. To be clear, what I'm looking to do is to click an option in my gui and have the selected player option spawn at a pre-defined point in my level.

Thanks in advance for any help!