Support Contacts Issue
Phone A is my phone as a mom. Phone B is the phone my 15yo uses. Both iPhones.
Background
15yo previous phone died. It can no longer turn on. We shopped for new phones, and got a new one.
At first, I was going to get the newer phone for myself (B), and my carrier began loading my stuff onto it. Plan was for my child to take my 'old' phone (A)
As we proceeded, we needed to go home to finish up on wifi. It hit me that I didn't mind my child getting the newer phone. I use my phone a lot at work, and I was having an extremely busy week--it was a hassle to switch. I'll get an upgrade later.
We got home and arranged for the carrier to switch our phones (at the phone number level). This happened successfully. (A) never really changed hands, had all my stuff on it through this process. (B) went from mine to hers (My iCloud existed on both phones for a little bit) by logging out of my iCloud and logging into hers. And again, the carrier support matched this process.
Problem
Phone A is mine, all good
Phone B is my child's, and it has my contacts
Her iCloud has her contacts. For example, I can log in to her Cloud on PC and see all of her own stuff there.
Everything else, besides contacts, seemed to move over for her, phone B seems to have all her stuff.
What step do I take to sync her backup to her phone, and NOT sync what's on her phone to her iCloud?