My child is using my apple id on her ipad. How do I get her set up with her own apple id without losing everything.

This post may help. https://discussions.apple.com/thread/252986782?answerId=255605342022#255605342022

Essentially, you'll need to remove all of your data. Reset the device, and set it up a new to her using her Apple ID.

If under 13 years old, you will need to set up Family Sharing to create an ID.

Family Sharing and Apple ID for your child.      

Family Sharing.         

Family Sharing - Set up.    

You don't have to remove all the data on her iPad. See my post in the link myguy posted.