> If vdb-A fails to load on deployment, I see vdb-B also fails.
Yes, that is expected.
> If vdb-B has multiple imports, but one of them fail, is it still possible to run vdb-B with other successfully imported vdb?
Not currently. It is conceptually possible and would just result in a lot of planning errors until the imported vdbs are available. Unfortunately with the way we do deployment and sessioning when an imported vdb did become available more than likely that would trigger a reployment of the importing vdb and terminate its current sessions.