While selecting the Windows device from the child’s Parental Control profile, you will notice a new window on the right side of the device. This will say “All Accounts”. Once you press on the Window, a list will drop down with all the Windows Accounts on the device and you can select a specific one.
Please note that you can’t add the device on another profile with a different Windows account as you are limited to one device per profile so you will need to select all the profiles or a specific one.