It is, of course, evidence of what we call The Folk Process, which is an essential / defining factor of an / the Oral Tradition. I think in the case of Derry Dems of Arrow we're seeing a very purposeful transportation of Child #241 into a western scenario. Do we know of any other versions that feature cowboys? Might even Mrs Stanley have done the work herself? Whatever the case, the Wild West frontier mythos provides a worthy context for the ballad, in much the same way that Sergio Leone reinvented Kurasawa's Yojimbo as A Fistful of Dollars - only 6 years after Hunter recorded Mrs Stanley! Being both a fan of Ballads & Westerns (Spaghetti & others) I must say this one appeals to me greatly.