My wife has storage back up under her Apple ID how can I get my phone to back up under that?
My phone need to back up. How can I use my wife’s I cloud storage? She has under her Apple ID
iPhone 12 Pro Max, iOS 14
If you wish to use or share your iCloud's storage, she will need to share it providing she has setup the Family Sharing (200GB or 2TB). As for backing up your device, that's all on your own and has nothing to do with sharing iCloud storage.