I don’t know if this will help anybody. But I’m posting this as a record of how this unique problem was solved.

Here is the procedure, to restore an H9 Max de-registered by a party other than the owner (including the additional variable of a second, algorithm-sharing H9 Core). The condition was a deregisterd H9 Max, that was not deregistered in it’s associated H9 Control. Cannot re-register because it is already registered in H9 Control. Cannot de-register, because it H9 Control reports it is “registered to another owner”. Both pedals reporting “No Algorithms”.

1. Clear account settings on H9Control device (eg. iPad).
2. The H9 Control will continue to report the H9 Max as registered. It will not permit deregistering, because it detects an H9 Core that may be sharing algorithms.
3. Log into the Core, restore it to factory settings and turn it off.
4. Clear account settings a second time in H9 Control.
5. Deregistered the H9 Max, and log out of H9 Control.
6. Log into H9 Control. It will detect the H9 Max.
7. Register H9 Max to the Eventide account. H9 Control now recognizes the local owner.
8. I logged out and back into H9 Control.
9. H9 Control will find the H9 Core, and allow it to be registered ito the Eventide account.
10. Restore both H9 backup files.
11. H9 Control will now accurate ownership, registrations, and bundled algorithms
12. Log into eventideaudio.com and check My Products. If it reports accurately, you are set. If it reports inaccurately, contact Eventide. technical support. They have the ability to correct their database.