You should do what @Str0ngkatTh1rteen was saying and “layer” the joystick values by adding them so that you don’t have to use if/else statements. Something like
FL = Axis3 - Axis1 + Axis4
FR = Axis3 + Axis1 + Axis4
BL = Axis3 - Axis1 - Axis4
BR = Axis3 + Axis1 - Axis4(idk if all the signs are correct, it depends on how you set up the motors, but that’s the basic concept)