I believe I have read that article before. i actually visited the library at Greenville and dug in the "stack of stuff". It turns out that the accident involving the 7th Miss. occurred on Aug. 1st, 1862. There was only one man killed from the 7th Miss and if memory serves me another may have died later.
What is interesting is that the "Big Train Accident" near Greenville was later and involved more fatalities and many injuries. I believe that many of the injured and killed were located at a camp of instruction; Pollard, I think. Does that make sense?
The articles I read described how all of the churches became hospitals and how the old cemetery was filled with soldiers from different states and units. I believe there were some lists, but the old cemetery was relocated and the graves became unmarked.
I am going from memory so I can't remember any more details.
I am sure that the people of Greenville tended to the injured in the August 1862 accident as well.