Hi bowmama2,
Remembering my son's teen years I can certainly sympathize with your situation. Let's see if we can set things on the right track.
In order to make your daughter part of your Family Sharing group, she will need to have her own Apple ID. If she is under 13 years old you will have to create this Apple ID. The following article gives the steps for doing so as well as how to set up the account and Ask to Buy -
Family Sharing and Apple IDs for kids - Apple Support
Note that after you associate a device with your Apple ID, you can't associate that device with another Apple ID for 90 days, so if she first set up the iPhone less than three months ago she can not change it to another Apple ID. See this article for reference -
Manage your associated devices in iTunes - Apple Support
She (or you) can dissociate the iPhone from your Apple ID. See this section of the same article -
Remove an associated device
To remove a device or computer from your Apple ID:
- Click to open your account in iTunes, or use these steps:
- Open iTunes, choose Store > Sign In, then enter your Apple ID and password.
- Choose Store > View Account.
- Click Manage Devices in the iTunes in the Cloud section.
- Click Remove next to the device that you want to remove.
When you remove your Apple ID from a device, the 90-day limit stays in place on that device. But you can associate your Apple ID to another device that doesn't have the 90-day limit. Depending on when you associated the device, you might need to wait to associate it to a new Apple ID.
Once your daughter has her own Apple ID and her iPhone is using that Apple ID, you can use the Ask to Buy feature of Family Sharing to approve or deny each purchase she makes. I assume that she is under 18 years of age, as Ask to Buy is not something that can be put in place for users older than 18. See this article for more information about Ask to Buy -
Request and make purchases with Ask to Buy - Apple Support
Thanks for using Apple Support Communities.
Best,
Brett L