Your great-grandfather George B. Mehl may be George Brinton Mehl. If that is the case, his parents were George Washington Mehl (b. Apr. 21, 1830 in Boselschausen (Bouxwiller), Alsace, France) and Nancy E. Davidson. They were married on Dec. 10, 1858 in Nobel Co., Ohio. George B. was born Mar. 5, 1865 in Gallipolis, Gallia Co., Ohio.
If this George is indeed your great-grandfather then Selena Dilley's great-grandmother Martha Mehl was his sister.
I have quite a bit of information on the Mehl family, but very little other than what I have just mentioned, on your particular line. If this connection looks correct to you, though, I can take your line back a few more generations.