cristian, asks how acceptable or necessary is it to adapt a trdional song in your own way.
the singer BobRoberts is an interesting case,he had an unusual version of, While Gamekeepers lie Sleeping,I suspect he touched it up and added bits himself,he is generally regarded as a traditional singer,.
and probably wrote the monologue, The Oily rigs[so he was performing contemporary material as well],yet he wasnt dismissed as a singer songwriter[he wrote swell your nets full]a modern song written in the traditional idiom.
I myself have added a verse of my own making to Whip jamboree, a traditonal song.
The song THREE SCORE AND TEN, a composed song[mid 1880,s]has survived to this day and is still sung,but it has acquired and also lost verses.
so it would seem that the alteration of songs, has been going on for quite a long time.
I saw recently, that Alan Lomax,had his problems with academics,so im in good company.