How to switch off vector nozzle?

Dear all,

I would like to set up FreeWing Su-35 with vector nozzles.

The vector nozzles are controlled by three servos.
Servo A is connected to two nozzles and acts as a ladder.
Servos B and C are connected to each one nozzle and serve as an elevon.

I would like to do the following using the 14SG Switch c.
on: Nozzles act as elevon and rudder.
off: Nozzles are fixed at center position.

Is it possible to make such a setting without changing the source code of ArduPlane?