I can't believe that long reply didn't post! Or that the mouse didn't copy it!

Short and less informative version: don't be fooled by the "Child numbers," "Roud numbers," "Laws numbers," etc. These are simply for reference and easy identification.

Nobody seriously refers to collections by the Lomaxes, Sharp, Harry Smith, or anyone else as "canonical." Maybe a breezy journalist would, but nobody else. A "canon" implies exclusivity.

A "canon" is as a "canon" does. Nobody would refuse to study a song just because it didn't have a number. In practical and realistic terms, there is no "canon" of folk songs or ballads.