Q: Changing Apple ID

Hi

Your wife needs to be signed in to iCloud on her iPhone with her own Apple ID and password:

- Settings > iCloud.

The watch can then be paired to her iPhone again:

- Unpair your Apple Watch and iPhone - Apple Support

- Set up your Apple Watch - Apple Support

I just did this exact same thing this past weekend when my wife and I got our watches. The links below were very helpful, especially the second one.

Change your Apple ID - Apple Support

What to do after you change your Apple ID email address or password - Apple Support

The only issue we had was she lost most of her contacts. I backed up the phone using my appleID but after the switch when I logged into itune with her ID, it treated it like the phone had never been backed-up so I could not restore from the back-up. Other than that, everything (including the new digital touch features) are working as described.