The James Abernathy and Elizabeth Abernathy who conveyed the deed in 1792 to Smith Abernathy were the son and widow of the James Abernathy who was drowned in 1785. They were the executors of his estate.
Another son of James Abernathy born 1743 and wife Elizabeth Cox was David Abernathy and his wife Martha Abernathy who was known as " widow Pattie of the Bissell Place " because James Abernathy b. 1743 and his wife Elizabeth had given David and Martha land.
From Abernathy Nixon's loose papers: ( James Abernathy bought the Bissell Rumfelt and Farrar places in one tract from Moses Bonner and his wife Charity in 1778. John Rockett's wife - daughter of James and Elizabeth Abernathy -was given the Farrar place and the Bissell and Rumfelt place to David and Martha - Pattie above. ) David and Martha Pattie are my ancestors.
I can't quite place your Rebecca who married Moses Farrar. That could be the same Moses Farrar who married Arpy Ann Duvall who was the widow of Robert Abernathy of Perry County, MO who was the son of Miles Abernathy and Sarah Ann Jones - the widow Goode. This Robert Abernathy had a store in Perry County,MO in partnership with George Rutledge which no doubt passed down to Robert's widow Arpy who may have passed it to Moses Farrar. This Arpy Ann Duvall was the daughter of John Duvall who was in Missouri before 1800 when it was still Spanish Territory. They all lived in the " Boise Brule Bottom " in what is now PerryCounty, MO where my ancestor Turner Abernathy lived from about 1812 to 1823 when he moved to Washington County, IL. Turner is the son of David and Martha ( Patttie ) above. I suspect that they all knew each other.
If I run into something on Rebecca Abernathy I'll let you know. Good luck.