Most of my information about Thomas H. Wallace and his family comes from his Civil War pension file. He served in Co E, 77 Ohio Infantry. Invalid application #245.413. Invalid Certificate #369.773. Widow's Certificate #446.374. I found his marriage record in his pension file, although it was sketchy. He married Mary E., 23 March 1863, in Belmont Co, OH. I realize that this doesn't mesh with the birthdate for Harry E., according to the 1880 census. I guess it's possible that Harry was from an earlier marriage?
His pension file listed his residence as Graysville, Marshall Co, WV in 1877 and 1881. It indicates that he was living there when he died, 23 Jan 1897. Possibly that would be another place to look for birth records for Thomas's children.
Do you have information on Mary, their children, and their descendants? I'd love to know more about them. I'm a descendant of his cousin, Lyda Jane (Wallace) Beveridge, and I have more information on his parents, siblings, and cousins. I've found pension files for his brothers, Nathaniel and James W. Wallace.