How to designate someone as a parent or guardian with Family Sharing

[iMore.com]

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.

Full story from the iMore Blog...