I am looking at implementing RLS in my multi tenant databases and was trying to think of a way of being able to extend access to a group of tenants rather than a single tenant. One tenant (the owner of the record) would create and maintain group access but I am not sure if this is possible (perhaps through heirarchyid). Also to make things more difficult our front end application uses elastic db tools and sharding so tenants may not actually exist in the same database. Has anyone tried this before and if so do you have any insight?