thank you
"..If you map two outputs to 1 heater then the single sensor will control both and the second sensor can be used as @jay_s_uk suggests..."
that sounds like a good starting point for me. Is it as simple as writing:
M308 S1 P"e0temp" Y"pt1000"
M950 H1 C"e0heat+e1heat" T1
to power booth cartridges synchronous from the sensor1 (T1) controller?