Situation: Software-1 on Platform-1, both certified.

Time-evolution: P1 is deprecated, replaced by uncertified P2, but S1 remains certified.. just nowhere certified to run yet.

Solution: There's another software S2 which originally vouched for P1, itself still certified, which can still be used to certify P2.

Counterfactual?: If S1 were deprecated in favor of new S3.. there'd be no plan to certify it!

The problem: None of this actually makes any sense! But we're trying to fake due diligence. Everyone knows the hardware/platforms kinda need to be certified with respect to each other anyway, but if we did it that way it would all be even more expensive an time-consuming.

Doesn't seem crazy to me. Which one do you suppose needs more proof of correctness: a cake recipe, or the oven you bake the cake in? The recipe has to be correct or the cake won't work, but the oven just has to hold a temperature.