Barnett was an immigrant from Donegal, Ireland. He married Susan Pyle and was a good friend of the Nolands when they were in Kentucky. He never came to Jackson County.
I have, also, seen the last name spelled McMonegal, McMonagal, MacMonegal and McManigle, but the spelling I am using is the most common spelling found. By my great-grandfather's time, however, the name had become McMonigal.
I seem to recall the name "Pyle" in my studies of the Revolutionary times, so that connection could be interesting to pursue.