If you live in a household where you need to monitor and control iTunes and App Store purchases that children are making, Family Sharing lets you do just that on any device that's running iOS 8 or higher. Once you've got it set up, you can even designate what adults in the group can make purchasing decisions for younger children.
How to assign someone as a parent or guardian with Family Sharing in iOS 8
Note that in order to assign someone as a parent or guardian, you'll need to be the family organizer, in other words, the person that set up the Family Sharing group.
Launch the Settings app on your iPhone or iPad.
Tap on iCloud.
Tap on Family.
Tap on the person's name that you'd like to assign as a parent or guardian.
Turn On the option for Parent/Guardian.
That's it. That person will now receive purchase requests from any children in your Family Sharing group. That means that if one person is busy and can't approve a request, the other parent can. You'll still only need one person to approve a request though, not both.