HI Richie,
Way back in 1985, Tristram Coffin tried to suggest some ways forward with this lament type in an essay you might find useful. He used 'Green Grows the Laurel' as his starting point but lots of what he had to say was relevant to 'Died for Love' songs. The essay is in Narrative Folksong New Directions eds. Edwards and Manley, p59. You should easily get a copy at your side. I don't fully agree with his approach as opposed to the stemmatic way we go about it, but it is useful to look at another approach, and his ideas would be helpful in understanding the whole complex genre.