William and Mary Ann Stewart Buchanan's son James was my g-g grandfather. I have info down from James, but very little past William. I believe William's father was William "Billy" Buchanan b. 1764 Lancaster, PA, d. 15 Jan 1790 Hopewell, Washington, PA.
William's mother Elizabeth "Betsy" Henry, b. 1768 Somerset, PA, d. 1825 Hopewell, Washington, PA