I have set up my son's iPad and my devices and computer with Family sharing, and all devices have Ask to Buy enabled. However, when my son attempts a purchase the screen indicates that a notification will be sent, but none arrives on any of my devices. Also, the purchase screen on my son's iPad says that I can approve it in person on his iPad, but there is no indication how to do that.
He has an iPad 2 running 8.2. I have an iPhone 5 running 8.4