Shared Apple ID- want to create new one I share an Apple ID with my mother...I know it’s not ideal but at the time it was easiest until she learned how to use the phone, plus we live in different states so I can manage the account. 

Anyway we now want to get her a separate Apple ID but I need to know if when we do this if it will make her lose all the stuff on her phone.  

How do I get to her current back up if I change and then use her new Apple ID.
Create a new Apple ID then add her to your account as a family member with the Family Sharing option. Any apps purchased under the original account will remain available (and paid for) in the new account. She would lose some things (account backups, for example, but her device would start backing up to iCloud on its own storage rather than using your free allotment). If you set the account up for her, you can still manage it as you'd know the login info.