The original title was "ExternalS3: Support multiple users / team in owner.txt" but I renamed it to reflect the problem rather than a suggested solution, "Allow multiple users to link a private bucket to Synapse".
Currently we can specify one user in owner.txt.
Any way this could be extended to multiple users or teams?
I often run into the case where I want to setup a folder for external
storage, then find out the bucket is setup for another user.