Hi GeorgeLaFlare,
For help with the Apple Music Family Plan, test the information below found in the article here: If a message says 'billing problem with previous purchase' or 'verification required' - Apple Support
"If you use Family Sharing
If you use Family Sharing and purchase sharing is turned on, the family organizer's payment method is charged for all family members' purchases. If you're the family organizer and you or a family member can't make purchases, change your payment method.
If you're not the family organizer, ask the family organizer to change their payment method. Or redeem a gift card and pay your unpaid order."
You can also pass along the information to have the Family Organizer check their payment method. If you need to change or update your Apple ID payment method and ensure they still are showing the correct Family Sharing membership for Apple Music with the steps here: Get an Apple Music family subscription
Should the issue remain, reach out to Apple Support directly to further assist and help check on your account details.
Contact - Official Apple Support
Contact Apple for support and service - Apple Support
Cheers.