Apple Watch from Sprint to AT&T?

She can connect it to her iPhone and not use the cellular feature. It will only work with one cellular connection and will have your phone number on it, not one of its own. When you pair it with your phone again you may have to contact Sprint to reactivate your cellular connection.

Watches are not carrier specific so they should work with any carrier you want to use.

Many apologies, I was distracted and forgot to answer the second part. deggie has been cleaning up my answers all month.

Not cleaning, teamwork!

You are too kind. Thank you.