This is how I have always set up a bib.
In the main program set up flaporons. this give you two channels for the wing. Next slave 5 to the elevator.
Starting with the wing. Set up the Rt. upper and lower wing using a Y to split ch. 2. Then do the same on the Lt. ch.6 Align the ailerons using the linkage. check the direction using the servo reverse function.
You do the same on the elevator. Each servo to it's own ch. One of the servos will have to be reversed. Align the servo horns using sub trim.
After your done with your set up set up the D/R on the DR screen this will work on all the ch.