This is something that doesn't yet exist. Once in a while an admin wants to move their subject source to a new one, or even just rename it, and it's a challenge. The whole system can break very easily, or lock everyone out, be generally nonfunctional, or lose audit history.

If you want to retain all the existing records from the members table and just swap out the subject source name, this is the easiest because you don't affect any memberships or history. You need to change the members + PIT members + provisioning members which reference the source by name. But you need to coordinate, creating the new source name, migrating the users, and disabling the old source name. If IDs and identifiers are not the same, you need to map the old ids to the new and adjust them in the members table. Then you need to account for any subjects that did not match, so they can be fixed manually or picked up by usdu.

If there were a UI or command line tool to do this, it would make things less fragile and less requiring experts to perform.