
Hi Kirstin, thanks for reaching out. My name is Bernard, a Windows fan like you. I'll be happy to help you out today, my timezone is UTC +8.
I understand the issue you have, there is nothing to worry I am here to assist. Do you still remember the email address you use on the different family account where you added your daughter? If yes, I recommend recovering the account first, then removing the child account. Another way is to create a new child account for your daughter if you cannot remember or recover the account. Kindly follow the steps below to recover the account:
Method 1. Recover a Microsoft account by resetting the password:
Go to this link: https://go.microsoft.com/fwlink/?linkid=2273955 and follow the prompt to reset the password.
For reference: https://support.microsoft.com/en-us/account-bil...
Method 2. If you cannot reset the password or are unable to verify the account, I recommend submitting a recovery form:
Fill up the form and wait for the reply within 2-3 days.
Note: If all fails, it is better if you can create a new account for your daughter.
Let me know how it goes and I hope that helps.
Bernard