Act'lly the origin of these tunez is unknown, even those that are claimed and copyright by people. They used be called 'strains' like bits or phrases which would end up in a couple of pieces. There is a lot of needless confusion on this topic.
The Scot and the Irish are always tradin tunez and songs so I tend to pay no attention to which is supposed to be the source, I just play em. My favorite right now is the Bonnie Broon ,I am playing it on anything I can find. I did not find the words in the DB I suppose they are listed under Laydie Faieee.