[maddoctor90]

<R56> Relay module outputs, speed controller outputs, or PWM outputs must not be connected to the analog/solenoid breakout boards or the Digital Sidecar. 12Vdc power must not be connected to any terminal on the analog/solenoid breakout boards or the Digital Sidecar except the designated 12Vdc input terminals. (Doing so may damage or destroy components of the control system.)

So, you can't use the 12v off of the sidecar. Although, I am not sure if you can use the 5v to switch a 12v source legally. At a quick glance at the rules, I think it would be ok, although I would want to make sure first for yourself. My team will be using three relay modules for about the same thing because it is easy and we know it is legal. I would suggest you do the same, unless you have some reason not to, or have extra time and feel like experimenting around.