http://www.freewebs.com/craighomepage/jacksontree.htm
I found this genealogy just after reading your query. I shows

1. Thomas Jackson b.bef 1765 d.Nov.1838,Donegal Twp.Butler Co.PA (May or may not be in error, )
+ unknown marr. n l t. 1789 bef.1775 -bef 1838
res.1790 Salem Twp. Westmoreland Co 1800 Buffalo Twp Butler Co1810 Donegal Twp. Butler County,PA
occ. Village blacksmith & Farmer
Reli: Presbyterian
Children: Eleven
2-1.Sarah Jackson b.1790 d. 1850 Fairview Twp .Former Donegal Twp. Butler Co. PA d/oThomasJackson
+ Alexander Craig b.1790 Westmoreland Co. PA d.aft.1830 He was2nd s/o John&Elizabeth( Betsy) Craig
Children: Three of Donegal Twp. Butler Co. PA
3-1 Daughter Craig b. 1810 d. ?
3-2. John Craig b. 1810 d.
+
3-3. Thomas Craig b. abt 1816 PA d.
+Nancy ? abt 1845
res. 1860 Census Parker Twp.,Butler Co.,Pa
Children: Five
4-1. Alexander Craig b. 1846
res: 1850 census Fairview Twp.,1860 census Parker Twp.,Butler Co.
4-2. Margaret J. Craig b. 1848
res. 1850 Fairview Twp. 1860 Parker Twp.
4-3. Mellessa Craig b. 1852
4-5. Sarah Craig b.1855
2-2.Haugh Callen Jackson b. 1807 d. 1884 s/o Thomas Jackson
+ Elizabeth Craig d/o James Craig & Granddaughter of John Craig
children:
3-1.James Craig Jackson b.abt 1845 d.2/1917 note:was in three different units during Civil War and + 1st ? b. d applied for a pension in 1877.Widow applied for his pension in Feb.1917
+ 2nd married in or abt 1900 to ?
2-3. Mary Ann Jackson b.1793 d.1879 d/o Thomas Jackson
+ Thomas Callen s/o Hugh Callen founder of Callensburg ,PA
child:
3-1.John Callen b. d.
+ Mary Ann Reddick (his first cousin) d/o William Reddick and Elizabeth Jane Jackson
2-4. Elizabeth Jane Jackson b.1804 d. 1871
+ William Reddick
child:
3-1. Mary Ann Reddick
+ John Callen
2-5.David Jackson b. 1791 d. 21 Mar 1845 Donegal Twp.Butler
+ Jane Ray b.1805 d.4/1862 d/o William Perry & Elizabeth "Ward" Ray
occ. Farmer
children: Seven
3-1 William Jackson b.1827 d.1862
3-2. Thomas Jackson 1829-1865
+ Elizabeth b.aft 1865
children: Two
3-3. George Jackson 1830-1865
+ Lavina or Elvirah
3-4.Alexander Craig Jackson (Twin) 1834-1914 census 1910 Bruin ,Parker Twp. Butler Co PA.
+ Catherine Lois Mortimer b.Apr. 1848 d/o Samuel Mortimer
Children: seven
3-5. James R. Jackson (Twin) 1834-1865
3-6. David Jackson 1837-1903
3-7. Elizabeth Ann "Eliza Ann" Jackson 1843-1865
2-6.John Jackson b. 1797 d. ?
2-7. James Jackson b.1805 d. ?
2-8. unnamed
2-9. unnamed
2-10. unnamed
2-11. Thomas Jackson b.1794 d. ?
I guess we are related somehow.