This is very helpful.Most of the immigrants of our Alexanders in the DNA group came well before the 1870's and STAYED here.You are lucky to know the uncles preceded Herbert and Thomas.
We have 2 different Alexander families from Armagh.
One's early Alexanders are: 1. James Alexander b ca 1732 in either Co. Armagh or Tyrone, d 1791 Clonmain, Co Armagh m Unknown Alexander b Abt. 1735 2. John Alexander b Abt. 1758Loughgall, co Armaghd1821 Cloveneden co Armagh Ireland m Sarah unknown b Abt. 1770 in Co Armagh, m Tircrammon, Co Armagh 3. William Alexander b ca 1795 Loughgall, Co Armagh, Ireland;d? Carleton County, Ontario, Canada, m Jane Culbert b Derrycorry, Co Armagh, m Tirmacrannon, Co Armagh d:Huntley, Carleton County, Ontario, Canada 4. William Alexander b 1826 Loughgall, Co Armagh, Northern Irelandd 1909 Tangambalanga, Victoria, Australia; m Rachael Irvine b 1833 Loughgall, Co Armagh, Ireland, m Beechworth Vic, Australia
The other family is this line: 1. Thomas Alexander b. 1661 Glasgow, Scotland d. abt 1720, m. Marion Peadie 2. John Alexander b. 9/27/1691 Glasgow, Scotland d. 1777 Chambersberg, Pa. m. Margaret Glasson 3. James Alexander b. 1726 Armagh, Scotland d. 1791 Clearfield, Pa. m. Rosey Reed b.1742 Chambersburg, Pa 4. Hugh Alexander b. 11/1773 Mifflin,Pa d. 1843; m. Christiana Baum
Naturally there is no way to predict who or if you may match.
It sounds as if you have more info elsewhere.Please feel free to post it or email me.Don't think I can help much other than opin.But I'll be glad to try.You have until the end of next Friday to save 30 bucks off the normal 150 buck test price.