Transfer Xfinity Mobile number to a different Xfinity Mobile account

Hello,
I need help transferring my wife's Xfinity Mobile line from my dad's account to my account. I called Xfinity Mobile support, but after spending half an hour trying, they said they couldn't do it because the phone wasn't supported??
It's a Moto G7 Power purchased directly from Xfinity Mobile.

Thanks in advance for any assistance!