Block my apps from behind downloade by my children

I have family accounts setup for my family so kids can search each other's apps and download apps that we have already purchased on their iPads without paying again. How do I make it to where the kids still have to request permission from me before they download apps from my account that I have downloaded. I use social media apps but don't want them to be able to download with out asking permission from me to approve 1st like they have to do when the want a new app that no one has downloaded?