Personally, I have no idea what the flags look like, made, issued, etc. Gregg and everyone on this site is the best on that. I just track down Union flags that were captured. Not many of the captured Union flags are around anymore, so finding them and taking pictures will be the most difficult part.
The Museum of the Confederacy has a few captured Union flags, most Northern states do as well.
Thank you and have a good day, Ben!
Shawn Prouty