I don't have any documents to back me up on this, but my memory is that Mike Seeger did (perhaps during the 80s) in-depth research on the family of songs relating to the Molly and Tenbrooks song and backstory. Somewhere I feel sure there are record liner notes or perhaps an article detailing all this (in Sing Out, perhaps?), and it would add depth to this discussion.

As for the relation to Skew Bald / Stewball, IMHO that is fanciful. I'm open to any genuine evidence to the contrary, but... the one is an Irish original adopted by American blacks about a race in Ireland. The other has to do with a known race at Churchill Downs. Knowing both songs pretty well and their respective histories, I see no likelihood of a cross -- at most a few accidental lines. The stories are distinct and so are the songs, with no persuasive intermediate versions that I know of. It's not impossible that some songster somewhere mixed them up and created a melange of verses relating to both stories, but that doesn't make a relationship between the two.

Reminds me of the old folklorists' fantasy, born of insufficient information, that "John Henry" and "John Hardy" are somehow related -- a canard that keeps getting repeated in some circles though it has no basis in fact. I do think it's important to avoid seeing relationships where there are none. Horse race songs are a small enough group without confusing them.

On the other hand the "Old Kimball-Old Nellie" and "Stewball" songs and stories do seem linked, though there's not much of "Old Kimball" to judge by, in any version I've seen (for example, Texas Gladden's). That bears more investigation.

Bob