There there Jaylou. Let me help. Dave Grohl, lead singer of the Foo Fighters and formerly of Nirvana and all round splendid drummer. Neil Patrick Harris - formerly child star in Doogie Howser MD, and Tiffani-Amber Thiessen, played Kelly (Zacs girlfriend) in Saved By The Bell, an eighties/early nineties American teen sit-com about a group of friends in high school.
Honestly, no bother.
As for my opinion on "Harper Seven", well Seven is frankly dire, but she wont be going round known by her middle name, so thats probably least said soonest mended. I personally dont like Harper, but Harper Beckham sounds ok. Harping to me is a word that means nagging, when someone "Harps" on about something incessantly, but if they stay in the states it will go unremarked upon as its more common there.
I've heard prettier names. S'all.