John, I've recently been corresponding with one of the researchers who's been working on this line. You mentioned in one of your prior messages in this forum a coincidence between the occurance of given names (Jesse, in that message) in some members of the David of Dinwiddie line and the David of Lunenburg line.
I have recently noticed yet another and possibly even more curious coincidence: in the line descending from David Abernathy of Lunenburg Co VA, there is Hardaway Teague Abernathy, b. 1800 in Virginia, presumably in Lunenburg County, and died after 1880, probably in Monroe County MO. In a sub-branch of the Robert (1st) Abernathy of Charles City County VA lineage, many of whom were then still resident in Virgina, in that same decade a son was born to James Burwell Abernathy and was also given that rather unusual first name: Hardaway Abernathy, b. 1806, d. 1852 in Giles County, TN and buried in the Hardaway Abernathy Cemetery there.
Directly related on this side of the Atlantic or not, methinks these people must have considered themselves close kin. And they evidently communicated amongst the various branches!
As to whether the younger David Abernathy of Lunenburg could have been related to the elder David Abernathy of Dinwiddie, he is of an age to be a son and there is an indenture deed (I don't presently seem to have a copy), evidently between Sarah (Blackstone) Abernathy's father and David Abernathy, Jr., which certainly adds more circumstantial evidence supporting the theory that the two might be father and son. However, I'm not altogether sure that we may ever know the answer to this, considering the loss of so many colonial records.