Sites in multi-site need the ability to specify the org/group pair that they represent

Each site in a multi-site configuration should be able to specify which org/group pair it represents. This is how multi-site and multi-org will work together, since often (but not always), multi-org and multi-site use cases overlap. An example of this is when state chapters are sub-orgs of a national org but still have their own domain names / websites (U.S. PIRG works this way, for example).