Family sharing

From what you say, it sounds like the daughter with three Apple IDs is 12 or under, and that this is where your main problem lies. I have never been able to find an answer to the question of how do you delete the Apple ID of a child 12 or under. I have posted what I have come to think the solution is a number of times, asking the poster to let me know one way or another is my possible solution works. I am doing the same thing now. Please let me know. Here is the possible solution.

Since you are talking about a child in the context of Family Sharing, see Family Privacy Disclosure for Children https://www.apple.com/legal/privacy/en-ww/parent-disclosure/. Toward the end of this document you see: this heading Access, Correction and Deletion. Here is a quote from it.

"If at any time you want to access, correct or delete data associated with Family Sharing or your child's Apple ID, please contact us here: www.apple.com/privacy/contact/."

Using the above link, this is where it may be appropriate pursue you deletion of a child's Apple ID (12 or under): Privacy Inquiries https://www.apple.com/privacy/contact/. Fill out the form provided on this link.

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Also if you need to adjust the age of the child showing up as an adult, see: 

Update the birth date associated with your Apple ID https://support.apple.com/en-us/HT204164 and

contact Apple ID Support to see if they can help remove the extra IDs.  See the Apple Support articles below for contact information.  

Apple ID - Official Apple Support.    

Contact Apple for help with Apple ID account security - Apple Support.   (Link doesn’t always load)  

Get Support          Work through the screens to get a chat option. You may have to pick a slightly different problem.

Apple Support schedule phone call

https://twitter.com/AppleSupport.          People have posted it may take an hour or more to get a response.

Thanks for the information, based on which I believe you will need to contact Apple support for help. This is because you cannot remove a Childs account from family sharing without adding it to another family sharing set up. This is done to avoid the possibility of a minor getting an account of their own without parental control. You can contact support using the link below:

https://support.apple.com/apple-id

Welcome to the Apple community.

I suppose the first question would be, does one daughter have an Apple ID with the wrong age attached to it and does the other daughter have three Apple ID's?

Is this daughter 12 or under? If yes, see my post above. I emphasize that I am uncertain about my possible solution.

You are welcome.