Apple Watch unlock

I would unpair the Watch then set it up without restoring the backup. The default settings will work, she just needs to add back the cards.

This will be easier than trying to plow through all the possible settings.

Check the equivalent apps on the iphone (Health, Fitness and any third party apps) If the data is all there then wiping the Watch will not delete the data.

In any case un-pairing the Watch will create a backup if it goes badly.

 Unpair and erase your Apple Watch – Apple Support (UK) 

Then set up your new watch as new watch

Set up your Apple Watch – Apple Support (UK)