The main "consumer" of Bayard's work was Bronson, but when he points to tune relationships he doesn't go on to say how they arose. It's like the early days of biological taxonomy before people could create timelines of DNA variation.

Any singers reading this? Do you internalize and make use of tune classifications in the way I described myself doing with instrumental tunes?

I just realiized I've ignored the most widely used classification method in the folk world - chord progression. That certainly has practical implications for its users.