Before you had to go on the iTunes app on Mac and then on your account purchases section. With iOS 8 you can simply go on the App Store Purchased section and then swipe right (left?) and a red "Hide" button appears.
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So you are using Family Sharing and have made purchases with iTunesStore credit? Not with that shared credit card?
Also, do you get that notification about purchases/approval even if you buy with iTunes Store credit?