I'm sorry about your situation.
I'm not familiar with the Devo 7 TX /RX . Can you use a Y connector for the two aileron servos and plug it into channel 1 ? Then, plug the elevator servo lead into channel 2 , throttle in channel 3. That's how many work. Might have to experiment with reversing. Have the wires going the correct way? Usually the light colored wire orientated inwards.
The Spektrum- like way would be: bind / throttle/ aileron/ elevator. Hopefully, someone here that knows the Devo can chime in.