I have a family member on my family account. They recently set up a recurring monthly charge for an app that keeps hitting my primary account, not theirs. How do I help them change that so it does not keep hitting my account?
From: How apps, content, and subscriptions from Apple are billed - Apple Support
● Some subscriptions might not be charged to your Apple ID balance.
With that in mind, if is something you think can be paid with personal balance, make sure the family member has enough balance to pay for items before they roll over to your account. Adding funds by using a gift card is a handy method.
How to redeem your Apple Gift Card or App Store & iTunes gift card - Apple Support
How to fix when a family member's purchase gets charged to the primary account by mistake
