I’ll let you know in an hour or so…
JEDIT: The SUP files are not compatible, and would still need splitting and re-timing even if they were.
It looks like you can import SUP with MultiAVCHD (again just based on what is posted in that doom9 thread - not my personal experience), so perhaps you can swap them out after the authoring process is complete? assuming the branching doesn’t make that difficult.