Perhaps I'm misunderstanding your solution, or you are misundertsanding SM-S in ONTAP 9.5/9.6. In this scenario (ONTAP 9.6):
- A -> B SM-S
- A -> C SnapVault
If you lose 'A' (SV source / SM-S source) and run from the SM-S destination 'B' (new SV source), the base snapshot required to maintain the SV relationship to 'C' is not present in 'B'. This is because SM-S does not replicate the SV baseline snapshot. You have to re-baseline from 'B' to 'C'.
It's the same in the scenario below for async SM, the base snapshot is not replicated by SM-S, so to maintain the async to C you would need to baseline the whole thing:
- A -> B SM-S
- A -> C Async SM
If you fail from A to B, you lose the async relationship to C. If you fail from A to C, B becomes redundant.