The surname of "McGohan" for Polly’s husband is apparently from the will of George McCormick, which seems not to have been very legible as Keith Laws has put question marks after Cranson and Crethin for Polly's sisters. The IGI, batch 7113306, p. 9, film 1235245, lists marriage of Martha McCormick to Samuel McCord, 11 Dec 1781, in Fleming Co., KY. Polly was sometimes a nickname for Martha, and George McCormick's children were probably born in the 1760's and 1770's; perhaps McCord was misread as McGohan. I'm not entering the marriage that way, though, because the evidence is weak – Polly is not a real common nickname for Martha (Patsy was more common), and McGohan looks something like McCord, but not a lot.