that diagram looks like what I'm trying to do, but just to be sure, here is my attempt at diagramming "what I'm trying to do."
Forgive me for its crudeness, I am at work and only have paint to draw with.
Obviously this only shows for one button and one input. I can't change the arrangement of either the Remote or Controller. Consider them black boxes.
This will be running in a car, so if the device requires a voltage to operate, I have 12v to power it.
I was hoping to find a "device" like I show, but I don't mind putting together components (diodes, resistors, transistors, etc) to build such a device myself, but I am so out of practice I would need values and even better model numbers.
I know I'm being a pain, but I really appreciate the help