You may not be able to answer this one but my research points to the following relationship. Rosebarry Lafayette Rayfield, brother of Sussannah Rayfield Stewart Ollis, was married twice. First wife was Mary Jane Stewart, daughter of Jonathan and Sarah Mauney Stewart who died 15 Feb. 1873. About 1874, he then married for a second time to Sarah E. Stewart who was born 1856/1857.
I think she is the oldest daughter of George and Sussannah Rayfield Stewart and that he married his niece as a second wife. There were only two Sarah Stewarts of the right age to be his wife and the other one was another niece, daughter of William Beatty Carlisle and Catherine Rayfield Stewart but we know who she married.
Have you ever heard anything along these lines? I have been in contact with the grandchildren of this family but never mentioned this theory before.