Not needing a ‘suspend’ function makes things a lot easier. Ok, in ospi.py there is a call to ‘check_rain()’. That operation lives in ‘helpers.py’. Follow how that function sets the values for rain detected. I’d start by coping that function, then mapping the signal to a different GPIO pin. Then look at the ‘program_running’ if statement also in ospi.py. That shuts down the zones if rain (or in your case now) your switch is tripped. You’ll need to add a new ‘if’ path for your function when the switch is triggered so that you can start your custom zones and do <stuff>. Of course this is a high overview, but following how that rain on/off works should get you started and close to your goal.