How do my family & I better control family purchases?

morechoice2020 wrote:

Repost: Is there any way to disable the ability for family members to make purchases without my authorization? I don't mind sharing what I have purchased, but I don't want to pay for my sister's in-game purchases or other purchases I don't know about without being asked first.

Only if they are under-18 : Request and make purchases with Ask to Buy - Apple Support

Also, I have given other family members iTunes cards and they have credit in their account but my charge card was charged after all of my credit was used. How do family members choose to use their credits on the shared family purchases?

It should do that automatically, you can't specify what is used. If it's not they should contact iTunes Support