Harold, as long as I am still alive and kicking, I intend to be "going after it" where this family is concerned.
To the best of my knowledge, this particular Frederick Abernathy had 2 wives (Betsy Gibbs & Eleanor Long) from whom I believe I have identified 5 named sons.
Frederick apparently followed the grown sons of his 1st wife to Missouri sometime between 1840 & 1850, probably after his 2nd wife & most of his youngest children died. I do not know much about the daughters. A Cemetery survey of the Old Abernathy Cemetery south-east of Marble Hill near County Rd 422 in Bollinger County MO reportedly finds Frederick Abernathy, 19 Jan 1791 - 10 Jun 1852.
A descendant of one of his sons has been located and his DNA tested, which decisively illustrates that this descendant is a near perfect match with at least half a dozen other living male Abernathys with extensive documentation tracing their respective lineages back to the 1st Robert Abernathy of early colonial Charles City County, VA.