We're fully committed to the data separation model (upgrade/downgrade, 60 seconds downtime to apply an update), but often come across the problem that a copy of the live UI file is taken for development some months prior to it being ready to replace its original parent and the access privileges, user accounts and passwords are out of date.
To date, we've had to check what accounts have been added or deleted since the development copy was taken, update the dev copy manually, reset temporary passwords and inform the users or database manager(s).
However, with the release of the FileMaker Data Migration Tool, we could clone our new development version, take a copy of the current live production version and use the migration tool to copy over the user accounts. A big step forward.
However, we have a tooltips and a versioning table in the UI file that needs to retain data from the development copy, not the live copy, as the data here will now be out of date. We considered writing a script to import these into the new clone, but that is additional work for each system. We're shortly going to test the procedure displayed in the attached PNG file, which we believe will allow us to use the migration tool twice during the upgrade process to achieve our goals. Although slightly longer preparation, all this is carried out away from the live server, so we can still apply an update in less than 60 seconds.
I hope this either stimulates additional input to improve the procedure or helps out someone who comes across the same issues we do.