Can't answer the other cases you mention, but will try to explain this one. Nathan Oliver joined the "Franklin Beauregards" but left before this company was assigned to the 7th Mississippi Regt. He later mustered in Confederate service with the 21st Mississippi Regt., Sept. 15, 1861. Although we don't know when he left the "Franklin Beaurgeards," but it had to have been before the first muster roll of Co. "E", 7th Mississippi Regt., August 20, 1861.

General Forrest regularly had his rolls checked to remove men who actually belonged to other commands. Numbers of men leaving one command and joining another without due process presented a serious problem to the Confederate military.