Cube Red PWM Outputs

Is there a way to allow the Primary FMU on the Cube Red to use all 14 PWM outputs? The default configuration is the Primary gets the AUX rail (only 6 outputs) and the Secondary gets the MAIN rail (8 outputs). When I am connected to the Primary FMU, I do not seem to have control over the servos that are connected to the MAIN rail regardless of whether the aircraft is armed. I want to understand how the redundant control works if each FMU only has access to some of the PWM outputs.