The other 4 motor driver on primus-X

Hey team, First of all I will appreciate the work done by all of you in the segment of drones.
Now I want to ask that can we use motor drivers M1-M4 for more drone motors and make it as a 8 motor drone with 4 arms, if yess then please provide me a method so that I can just pair the commands to the simultaneous motor drivers (eg. M1 driver command exactly same as M5 command), Moreover to this I also want to buy the bigger battery separately which comes with the quad expansion kit.
pl. doo the needful,
-Avichal.