Family purchases and payments - https://support.apple.com/HT201079 - "When you set up purchase sharing, one adult in the family—the family organizer—agrees to pay for any purchases that family members make while they're part of the family group. With Ask to Buy, you can manage what your family purchases. And it's easy to change the payment method that you usehttps://support.apple.com/HT201079
So only one person can pay with a credit card and has to promise to cover purchases made by others. If others have a balance in their account from gifts or gift cards that will be charged first, otherwise it will be taken from the single credit card for the family.
You can also limit child purchases with Ask To Buy
Request and make purchases with Ask to Buy - https://support.apple.com/HT201089
Ask To Buy can only be turned on for members up to 17.