“Marriage Records of Highland County, Ohio (1805-1880)” by David and Jane McBride, copyright 1962, page 155 shows that Joseph Miller and Amy Overman were issued a license on 3 April 1851. It was not returned and the exact date of marriage was never recorded.
I have an Overman connection and have in my files:
Elijah Overman b: 14 May 1814 m: 02 April 1832 in Highland Co., Ohio to Rebecca W. Spargur b: 23 February 1818 in HCO d: December 1905 in Villisca, Iowa.
I can't recall where I got the death info on Rebecca and apparently did not find Elijah's death. Elijah had a cousin, Sarah Overman Newby, who was my 4th great grandmother.
good luck, Steve
Sorry, I can't tell you anything about Joseph Miller.