I have not worked the Nolens who lived in Fisher County, but I have recently found that Isaac Marion Nolen 1799-1878(son of William 1759 and Mary Ann Cockrell) was married twice. He first married Mary "Polly" Menix and had 13 children. He then married Mary ann Wislon and had 4 children, one of which was a twin called Stephen Jasper Nolen b 1856 d 1931 in Fisher County.
This Robert Troy Nolen was the grandson of Stephen Nolen 1830- d 1915 in Eastland County, Tx) Stephen, Son of David b 1757... was the nephew ofWilliam 1759 since David and William were brothers. So we know Isaac Marion Nolen and The Stephen in Eastland were related, however a ways back.
I need to know some dates on your William since there are so many Williams.... Milda Nolen Mason