You said 2 motors, so u have a 2nd PSU doing the same thing, right? In this this case this is a fully opened/Fully Closed setup, what are the motors make? This will give a picture of what can be done, the easiest part is to install a Shelly 2.5 behind one of the 2 switches to drive both of them, u will be able to control them from C4, as well as manually from the switches!
Problem with the Shelly it need a 30-50vdc input to operate with, I can’t think of anything in the market operates with 24vdc.