Is it still possible to swap 3CX licenses?

Back in the day of 3CX v18, we bought a few licenses which we registered to our own company to act as a cloud provider for VOIP. Thus, we would setup Tenant 1 on a 4SC license, and Tenant 2 on a 8SC license (based on size and usage). And sometimes, if Tenant 1 required the 8SC license and Tenant 2 only needed a 4SC, we would swap the license no problem to keep everyone happy.

But now with 3CX v20, is this still even possible to do? For reference, the same Tenant 1 and Tenant 2 are still running v18, and we would like to upgrade them to v20, as well as swap their licenses to handle their concurrent call needs. We tried backing up their v18 instance (without License Key Information, FQDN & Conference), and upload the backup when installing v20, but the install fails at the last minute. So we have no clue if license swapping is available anymore for legit 3cx license owners (with license registered to their own company).

Anyone have any success in swapping licenses during an upgrade from v18 to v20?