Perhaps add a couple of schottky diodes to isolate the supplies:
+5V --10K -|>|- G -|<|- 10K -- +12V
G can still be connected to Gnd, but 12V current cannot flow to 5V and 5V current cannot flow to 12V.
Perhaps add a couple of schottky diodes to isolate the supplies:
+5V --10K -|>|- G -|<|- 10K -- +12V
G can still be connected to Gnd, but 12V current cannot flow to 5V and 5V current cannot flow to 12V.