I have the marriage of Elijah Abernathy to Nancy Sullivan on 30 Aug 1830 in Lincoln County, NC, bondsman Isaiah Abernathy, source Curtis Bynum's "Marriage Bonds of Tryon and Lincoln Counties, North Carolina", Catawba County Historical Association, Inc Newton, NC (1929), p. 9. Both Elijah and Isaiah signed the marriage bond with an X, indicating that neither could sign their own names.
Elijah and Nancy remained in NC until about 1838 at which time they moved to Wayne County, MO. From census records the children, in order of birth, are: Lucinda, William M., Susan, Mary, Ursula, Miles, Marcus, Mahala, Samuel, Sarah J., and Margaret L. Abernathy. I do not yet know where they were in 1870 or 1880. The first 5 children were born in NC, the remainder all probably in Wayne County, MO.
I suspect Elijah, Isaiah, Frederick, Joseph, and several other Abernathy heads of families found in Wayne and Bollinger Counties MO from that point onwards may not be closely related to the bulk of the Abernathys found in Perry and Cape Girardeau Counties MO, but I do not know for sure.
If you do manage to track down a living male Abernathy descendant of this family, please do inform me.