Well done, Joy!! I know how hard and long you have been working on this and how exciting the journey of discovery has been. I have been very aware in all my researching that a lot of "facts" you find in print are either not referenced, or are based on another book that also isn't referenced. I think with this particular song there is a great chance that a lot of times that Lincoln is linked to the "other" version is that the linker has just assumed it was that song version.

In The Real Lincoln By Jesse William Weik and Michael Burlingame (originally published in 1922) they say that "Mr Lincoln's love of joking, for which he became famous in the latter days of his life, was quite as marked in the earlier period". His best friend when he was on the law circuit was Ward H. Lamon, "a mediocre lawyer" known to his friends as 'Hill'. When they were together with friends and Hill had had enough to drink, Lincoln would say (according to Weik and Burlingame):""Now Hill, let us have some music' whereupon Lamon would respond by rendering the plaintive strains of 'The Blue-Tailed Fly' or 'Cousin Sally Downard'or some other ballad of equal interest but of less propriety."

The time of the above singing would have been during Lamon's professional association with Lincoln which started in 1852, when he became Lincoln's law partner in Danville Illinois (where the singing is said to have taken place) and 1857 when their partnership in law ceased.(Wikipedia)

This is all very interesting. It isn't referenced as far as I can tell. It intimates that Lincoln had a sense of humour early in his life and again that the Blue-Tailed Fly was well known to him when he was on the law circuit (ie before he became President). Also the use of the word "plaintive" with the song.. suggests a sad song but who knows? Are they jumping to conclusions too?

keep searching Joy!

signed
your partner in crime