Would you happen to know the middle initials of the brothers?
There is a Franklin L. Cunningham & a J.S. Cunningham in the 1st TN Cav. Co. D.
Have you ever taken a look at the 1890 veterans census? Sometimes you'll find Confederates listed even though this census was for yankee vets.
How were these men listed on the 1850 & 1860 census, full names or initials?
Did any of these men survive the war? Die during the war? Apply for Confederate pensions?
Darron