My family has been using the same Apple Account across several different devices for years. After one family member moved to a new iPhone, the Photos libraries became mixed together, so our personal pictures now appear on each other's devices through iCloud Photos. How can I stop this syncing and remove my photos from the other person's phone without accidentally deleting them from all devices? We tried creating a separate account for her, but her personal email apparently isn't being accepted during setup. I'm worried about losing our photos and need to know the safest way to separate everything.
2 Answers
Using one Apple Account for multiple people will always mix personal data, including Photos, contacts, messages, and backups. A new account should be created with an email address that can receive mail and hasn’t already been used as another Apple Account login. If the email is rejected, try creating the account through Apple’s account website or use a different address, then add everyone to Family Sharing instead of sharing one login.
The safest solution is for every person to use a separate Apple Account. First, make an independent backup or export of each person’s photos before deleting anything. Then sign out of the shared account on the device being separated, choose the option to keep or download a copy of the photos when prompted, and sign in with the new account. Don’t start deleting photos until you’ve confirmed that the needed originals exist in a separate backup, because deleting synced photos can remove them from every device using that account.

That makes sense. I’m mainly worried that deleting the pictures from one phone will erase them everywhere before we finish separating the accounts.