I don't know if you were aware of this, but Swett's Battery was officially re-enacted in 1975 by (then) Governor Wm. L. Waller. It's commander was Capt. Franklin L. Ward out of Decatur, Illinois. I am his youngest son and we were in to reenacting from '74 to '78.
I remember driving to Jackson to mett with the governor and also over to Vicksburg to meet with St.John "Dell" Swett, and his wife. They were very gracious people and we had a very nice visit.
I joined the army in '77 and went over seas and my parents moved to Georgia in '78. I don't really know if anyone stayed behind to "carry the torch" after that, but I have a good deal of photos from that period, if you are interested I will post them for you.
DW