I ran across your question on GENFORUM.I don't have a lot of information but here is what I have.
Sarah Johnston (There seems to be some confusion as to the name being Johnson or Johnston) was born 1746 in Ireland or Scotland, Died 1821, Married Thomas McMackin abt 1764 in Botecourt Co., VA.Her father was John Johnston.
George Bailey Wilson was born 1764 in England or PA. Died 14 Aug 1834 in Butler Co., KY. Buried in the Stone Wilson Cemetery, Butler Co, KY. Married Nancy Agnes McMackin on 4 Apr 1786 in Greene Co., TN.His parents were John Wilson and Elizabeth Johnson.
I hope this helps. If you have any additional information, I would certainly like to have it.Thanks