How to change child’s phone number on account

Hi melaniefromcoldspring,

Thank you for participating in the Apple Support Communities. It looks like you came from the following support article: Add a family member to your shared subscriptions - Apple Support

If you need to change the birth date for a child under 13, reach out to Apple Support here: Contact - Official Apple Support

Here's a link with more details on that: Update the birth date associated with your Apple ID - Apple Support

Have a great day.