We both wish that Big Genie of Flags would open up and tell us all we need to know for the flags at Chickamauga as well as several other key questions we all still have!!! But we all keep chipping away on it and we will find something sooner or later that will help.
The Hardee flags used at Missionary Ridge (with the vertical ovals) were being made around the time Chickamauga was being fought based on the invoice I have fo flag maker Jacob Gall (19th Louisiana Infantry detached as Hardee's tailor in May, 1863). So the Hardees in the battle would have been earlier versions probably similar to the flag of the 17th Tennessee with the last battle honor (if any) being for Murfreesboro.
In so far as the flags of Ft. Donelson, it was not the fault of the troops that their leaders were morons! Forrest proved that the bulk of the garrison could have gotten out had their simply been the will to do so. So using those flags would not be that bad - and the 32nd's First National is stunning! Their Buckner/Hardee flag would have been identical to that of the 24th and 3rd Tennessee - white hoist edge with the rest of the exterior borders being double hemmed blue. The disc is sewn to one side and the blue cloth is cut away. The unit designation is painted on the flag. This would be easier to make.
I do indeed do Ft. Donelson Campaign tours from Cairo, IL to Clarksville, TN. I have a one day tour next Saturday in fact for the Tennessee SCV Division. My email is Biggsk@aol.com so drop me a line.