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Chuck, here’s my diagram with IGN ON. Note it shows the in-active control air connection between the top and bottom norgren (Level Low norgrens) – which is technically there during the IGN OFF configuration as well.

HOWEVER – the inflating balloon in your picture illustrates a situation that I would not have expected. The inflating balloon is on the exhaust port of the bottom Level Low norgren which would indicate to me that the top norgren has an internal leak as it should not be passing air across the connection to the bottom norgren (which agrees with your thinking above). And since the bottom norgren’s ‘normal’ connection is to it’s exhaust port in the IGN OFF configuration – you’re seeing the balloon inflate.

I chose to not show that in-active control air connection between those two level low norgrens in a IGN OFF configuration because the 5-port norgrens for drive axle are in a neutral configuration and thus no possible way to connect to the level low norgrens if operating correctly. What I think you’ve illustrated is when they don’t operate correctly (e.g., leak internally) then all bets are off. Which also in a way supports Jon’s scorched earth approach.