unforgiven3091 all you have to do is connect the on/off output to the input of the Plane Alt Hold controller. You connect your on/off button the input on this microcontroller instead. Once that is done give it the altitude you want via your keypad to both controllers and the current altitude to both controllers. If that doesn't help let me know and I'll attempt to explain it more.

i cant figure out where i connect the output to in the main microcontroller