I have one traditional version of Mallet's "William and Margaret" which is likely from a print source.
Of the traditional version about 10 versions attribute Margret's death to falling out of her window or jumping from her window. Less than 1/2 have the important opening stanza
Sweet William he rose one morning in May, Himself he dresses in blue. His mother asked him about that long, long love [That] Lies between Lady Margaret and you. [Sweet William- Nora Hicks]
which is found in Child B but not in the broadside.
A more recent adaptation named "Little Margret" first collected by Bascam Lamar Lunsford and published in 1929 has become popular and there are dozens of cover versions and some traditional versions found in the Madison County/ Sodom Laurel area in North Carolina. Sheila Kay Adams; Betty Smith; Obray Ramsey and others (including the Wallin family) have recorded this short version. Another popular rendition is the Carolina Chocolate Drops' version.
Betty Smith has commented (above) that William died from kissing the corps of Margaret, the revenant kiss, as found in other ballads (Child 49).
TY for your help and I've about "taken my fill" with this ballad.