Ron & Rick,
Ya'll must also consider the marching order of the regiment.
This was usually alternated daily (so one unit would not always be eating the dust of everyone else). A battle formation would shake out in the quickest and most convenient method. One particular company would not always be the "center" or the "left" flank.
Regardless of what the "parade-ground" movements should
The Color Guard and Colors may have had a particular spot
on the line, but, the companies themselves usually just
I have seen several regiments designate "Color Companies",
but, this was usually because they had the nicest Company
flag whic was adopted as the Regimental Colors.