I also copied a tree from the Edinburg Library for Peter Miller, Jr. who married Christena Hisey. That shows your Elizabeth Miller who married Nathaniel Barton (there is no sourcing for any of these people):
Peter Miller, Jr. b. 1788 Shenandoah County, son of Peter Miller, Sr., and Catharine Holler. He died 1864.
1. Elizabeth Miller b. 1809
+Nathaniel Barton m. 16 April 1836 (divorced)
a. Mary Jane Barton b. 1837 m. Jacob Estep 10 Nov 1840
b. Sarah Catharine b. 1840 m. David H. Hottel 21 May 1863
William H. b. 1844
Alexander b. 1846 d. 1924 m. Elizabeth Emily Thompson
f. John Josia b. 1848 d. 1916 m. Rebecca Painter
g. Ann Elizabeth b. 1850 d. 1932 m. William M. Furr
Nathaniel m. 2nd Catharine Hupp Coffman, widow of Henry Coffman
Nathaniel m. 3rd Sarah C. Hottel 14 April 1862
2. Joseph Miller b. 16 June 1810 d. 16 Jun 1864
+Sarah Hausenflude m. 28 Mar 1831
a. William H. b. 1832 d. 1910
b. John Henry b. 1834 d. 1848
c. Peter C. b. 1839 m. Sarah J. Barton 14 Jeb 1858
d. Sarah Catharine b. 1841 d. 1914 m. Joseph M. Barton
e. Mary Elizabeth b. 1842 d. 1897 m. Isaac C. Barton 28 Dec 1865
There are four more pages of this tree that I'll gladly send to anyone who is interested. There is one more child of Peter Miller who married a Barton, Mary Miller b. 1819 m. William Barton 6 Nov 1839
There are other crossovers in the family of Peter Miller and William and James Barton. I'm trying to find a family for my Timothy Miller b. ca 1782 whose son Thomas b. 1832 m. Margaret Barton, daughter of Matthew Barton and Mary Boyd. The bondsman for the marriage of Matthew Barton and Mary Boyd was William Barton shown as a son of William Barton in the Barton Tree I located.
All of this makes me want to find my Timothy Miller somewhere in the Peter Miller tree, but there is never any mention of him. In three independent sources after Timothy's death he is said to have been born in Kentucky. He was in Shenandoah County by 1820.