George, Shortly after the war contractors were paid a few dollars to reinter Union soldiers to National Cemeteries and needless to say some Confederates were taken as Union soldiers. Nothing was paid for disinterring a Confederate soldier and so the element of greed sometimes came into play.
Not all of the Confederate dead were taken to a National Cemetery after being killed at Chickamauga and a few were taken home.
The Western and Atlantic railroad was in Confederate hands during September and October 1863 and went to Atlanta, Georgia initially from Chattanooga, Tennessee. Was there a railroad at or near Walthall County, Mississippi? And if there was did Union forces destroy and hold that railroad in either parts of Alabama or Mississippi? My knowledge of Confederate railroads is limited and some railroads lines had different gauges at times but all railroads in Georgia should have been intact in September and October 1863.