My apologies--after years of no replies, I kind of neglected my post. Simply Googled my Dad's name on my iPhone, past midnight fighting sleep.
In our case, I don't think there's a connection. I believe the "Hampton" was from my father's paternal side, and "Sullivan" was the maiden name of his mother's mother.
The Harringtons and Sullivans (Dad's maternal side) were already in Polkton, NC when my dad's paternal side came into that area.