I am descended from Nathaniel's brother Jonathan Sartle/Sawtell Alexander b. 1749 Fort Dummer Brattleboro Windham, Vermont, d. 7 Mar 1838, Mexico,Oswego Co., New York. Jonathan also fought in the Revolutionary War.
Their parents were John Alexander b. 15 Nov 1709, Deerfield, Franklin,Massachusetts, d. 22 Jul 1755, near Fort Hinsdale, NH. John Alexander was killed by Indians.Their mother was Bathsheba Sawtell b. 1 Oct 1721, Groton, Middlesex, Mass. and d. Abt 1763 in Vermont.
I have additional information about the Alexander family going back a number of generations to the family's immigration in the 1630s.E-mail me if you want more. I will be happy to share.