Separate payment options in family sharing for each parent

Oddly, I responded just a little while ago to the same query. I'll paste here what I wrote in this thread. I hope it works for you too. It seems your group is set for payments by the organiser:

According to Apple's support documents your Family Sharing group has Shared Purchases turned on. In this mode the organiser is responsible (and billed) for the family purchases.

See How to download apps and content that your family members purchased

If Shared Purchases is turned off each family member is responsible for their own purchases, but cannot share their purchases.

See: Turn off purchase sharing in How to share purchases with your family

1. See your Purchase Sharing settings in Settings on your iPhone or iPad or in System Preferences on your Mac.
2. Turn off purchase sharing:

On your iPhone, iPad, or iPod touch, tap Stop Purchase Sharing.

On your Mac, click Turn Off, then click Stop Purchase Sharing.

Pleasure. I must get around to taking my own advice. My own family is now old enough to pay for their own content and I can do without most of their music on my account.