Thunderbird: Replace profile with one extracted from a backup

Helping a friend with a Win11 desktop PC.

Because restoring recent image backups did not fix her Win11 problem, I had to restore a backup of the C drive that was done in March 2025 when she first bought that PC. That resolved the Win11 problem. But now Tbird lost all of her email contacts.

I can extract Tbird's profile from a recent backup that was done in August 2026. Not sure if the name of 2026 profile will be identical to the name of the 2025 profile. If the names are different, Google Ai says to:
1. Insure Tbird is not runnng.
2. Delete the entire contents of the 2025 profile folder.
3. Paste the entire contents of the 2026 profile in the 2025 profile folder.

I asked Google: After I paste a copy of the 2026 profile folder in the correct location, couldn't I just rename the 2026 profile to the name used for the 2025 profile? Google said that would not work and that I should use the delete/paste method. What's the difference in doing it by deleting/pasting or renaming?

Or a better way?

I would mount the recent drive image and navigate to the Thunderbird profile folder.

Copy the contents of the mounted drive image TB profile folder to the TB profile location on the users drive.

I would google using the profile manager of Thunderbird. You can have multiple profiles at once, and select between them.
So I would keep the existing profile intact, use the profile manager to create a new profile, then copy the backup data into the new profile location.
Once you are happy with that, you can set the new profile as the default at Thunderbird launch, and then later delete the old profile if you want to, or just keep it for backup.

ref: using multiple profiles in Thunderbird