Greg,
I'm starting to think maybe I need to sit in the corner wearing a pointed hat that says "Dunce" on it. A while back someone (possibly you) told me that a good rule of thumb is that regiments that are brigaded together tend to be issued similar flags. Law's Brigade consisted of the 4th, 15th, 44th, 47th, & 48th Alabama. In the ADAH there is a flag that belonged to the 48th Ala. that is an ANV 6th Bunting issue. That, in and of itself, kinda blows a hole in the theory of everyone in Law's Brigade, much less, Field's whole division, carrying a 4th Bunting at Appomattox. It may be possible that Yelverton confused a 6th or 7th Bunting flag that the 15th was carrying at Appomattox with the 3rd Bunting the 15th (probably) carried at Gettysburg. The flags are very similar in appearance and, depending on when his account was written, the intervening years may have blurred the memories some. All of this is conjecture and will, unfortunately, probably have to remain so.