Detect which controller pressed a certain button

Hey guys, I'm working on a local multiplayer game that uses multiple controllers (joysticks) on the same computer/console. I downloaded the InControl asset that should help with the input, but I can't find a way to detect which of the connected controllers was used to perform some action (i.e. on which controller was the button pressed). The application detects the actions properly, but it doesn't make any difference if joystick 1 or 2 "sent" the action. The only way I could accomplish this is to define specific axis (or more precisely, 20 axes for each controller) in Unity's input manager, but that seems too crude, and very unpractical to use within code. Is there another way to know which joystick performed the given action? Thanks