As far as I know, a Confederate infantry company consisted of three Lieutenants, First, Second and Third.

The Third also called Brevet 2nd Lt., or Junior 2nd Lieutenant.

According to my copy of Hardee's Manual, 1861, the 2nd Lt. was assigned to the First Platoon, the 1st and 3rd to the 2nd Platoon.

I have been unable to ascertain the duties assigned to these three Lieutenants, nor of any hierarchy of the 2nd, 3rd, 4th and 5th Duty Sergeants, if any