I will try and add this info.
Robert Hart 1703-1770 married Mary Washington
Thomas Hart 1710-1797 Married Susannah Rice
John K Hart 1742-1832 Married Hannah Johns
David B Hart 17780-1835 married Matilda Kemer
John Kemmer Hart 1804-1874 married Harriett Burress
While I was going through this, I found that some of my links are wrong or there are a lot of Sr/Jr I didn't place right. I will try and look at all again asap and let you know what else I have found. I see now that Robert couldn't have been Thomas's father as the dates don't add up. Maybe there is a Thomas Sr and a THomas Jr.