a song is more likely to be processed ,if it has been sung a lot ,but some of the child ballads,have not,the sheath and the knife[among others] for instance,yet it is not discarded as a folk song,because of its rarity,neither was it discarded because it had not been processed .      neither was the Recruited Collier discarded because only one person collected it,[IMO]THE RECRUITED Collier is a folk song regardless of whether it is a modern composition,or whether it has been processed.
it is a folksong because of its style,its quality its melody and its words.
not only is the melody important but also the style of the lyrics,study the old child ballads,and we find certain lyric styles emerging.
30 years ago, very very few questioned the Recruited Collier?why because it sounded like a folk song,it should not be denied that term just because it has not been folk processed and turns out subsequently to be possibly a modern composition.