Combine controllers into one virtual input, or allow one controller's controls to be read as inputs on another controller

[FalseLight27]

May be a bit of a niche request, but this would be a godsend for people who love to use multiple controllers on games that don't allow it. This can be overcome by mapping/macroing one controller to the keyboard, but even then, the controller that is mapped to keyboard can only use mouse gyro, which isn't as smooth as mouse joystick gyro. Plus, games tend to turn off rumble when using a gamepad with the mouse and keyboard.

A good example is GTA V. I have my left-hand controller's left stick mapped to WASD, and I point and shoot with the right-hand controller. When not using the left stick, I get rumble, but as soon as I move it, I lose the rumble.