I have been doing research on this part of the Adair Family myself (william M. Adairs descendants) lately. I lived with James Adair and his wife Darlene as a foster child for 10+ years during the 80's and 90's.I actually consider them my parents sinced they practically raised me during the important years.That said, Mary jane's twin William Adair had a son William J Adair, born May 25th 1888 in Illinois and a daughter Nina Blanche Adair born August 20th, 1884 in Illinois.
William J Adair and his wife Lottie Matilde (b.January 27th, 1890D.1980) had 5 children:Martha Adair B. 1918 in Kansas; William Adair B. 1921 in Sudan; Anne AdairB. 1923 in Sudan; James Adair, B. 1925 in Kansas; and John Adair b. in 1927 in Sudan.
I know too that even after everyone was born, they traveled back and forth to sudan and egypt for missionary things,My dad, who became a minister as well as his brother william did, used to share stories about being there during my youth.
As far as I know, John and Anne are the only ones still alive.William, Martha and James passed away (James in July of 2004, not sure about the other 2 yet.)
I have a lot of information that I couldnt put on here that I have found also, so please feel free to e-mail me if you need more information.