Managing payment of family shared accounts by multiple owners

In Family Sharing if you have Purchase Sharing turned on, then only the Family Organizer is charged for any purchases and subscriptions unless the person initiating the charge or subscription has enough Apple account balance to cover the cost of the purchase or subscription.

If you want each person to be charged for what they purchase, then you need to turn off Purchase Sharing for the Family Sharing group.

click here ➜ Turn off purchase sharing and stop sharing a payment method - Apple Support

markuswin wrote:

Thank you for your answer. I was hoping that every person over 18 years old can be a family organizer and that this role is not only bound to a single account.

Sorry, Family Sharing does not work that way.

From: Set up Family Sharing - Apple Support

One adult in the family — the family organizer — can set up Family

Sharing for the group from their iPhone, iPad, or Mac. If purchase

sharing is turned on, the family organizer pays for family members'

purchases and must have a valid payment method on file.3

If they are able to pay for their own purchases, then Family Sharing seems unnecessary in your situation.