My direct ancestor was Abraham Bly - older brother of your ancestor James Henry Bly. Their Parents were John Bly and Charity Adams. John's father, David, was 25 years old in 1780 when John was born and so David was born in 1755 and married a Mary and sold land from Amhurst County, Virginia in 1782.
John's wife Charity Adams was born in 1785 had a daughter Henrieta -
That is all I have been able to trace. I would like to go further up both the Bly and Adams trees, but have met a dead end. Can you help?