The obverse side of the remnants of the 15th NC's flag has the three battle honours LEE'S FARM, SOUTH MOUNTAIN and FREDERICKSBURG. Looking at the way these honours are arranged leads me to believe that the flag originally had four battle honours repeated on each side of the flag. These were the three honours listed above as well as SHARPSBURG.
If you want to send me your e-mail address I'll send you a scan of how I think these honours were arranged on each side of the flag. My address is ritoews@mts.net
Ryan Toews