Hello BRWilkinson,
Thank you for using Apple Support Communities. That's a great question to ask. As you mentioned, purchases are linked to a specific Apple ID. This is also the same, when it comes to iCloud data. If your daughter was syncing your data to iCloud (Messages, Photos, Notes, Contacts, etc), they will be linked to that specific Apple ID and can't be merged to the new Apple ID.
If your daughter wasn't syncing with iCloud, she should be able to restore her photos and most data that isn't linked to the old Apple ID. The best approach to take, is to attempt and regain access to her old Apple ID. If she forgot what her Apple ID or password, please review this resource here: If you forget your Apple ID or password - Apple Support
Reset your Apple ID password with the Apple Support app on a borrowed device
If you don't have an Apple device but have access to your trusted phone number, you can borrow an Apple device from a friend or family member, or use one at an Apple Store.
1.) Open the Apple Support app on the borrowed Apple device. If needed, you can download the Apple Support app from the App Store.
2.) Scroll down to Support Tools, then tap Reset Password.
3.) Tap "A different Apple ID."
4.) Enter your Apple ID, tap Next, and follow the onscreen instructions to reset your password.
We hope this information is helpful. Cheers.
