Is there a ballad-by-ballad commentary on Child anywhere? I'm thinking of something that would go through each ballad printed by Child & document

where Child got it from (as far as we know)
any concerns expressed by Child and others (e.g. Chambers)
any reasons we might now suspect major rewriting or outright fabrication (e.g. single sourcing)
and conversely any examples of the same or a similar song being collected independently - for instance, Child only had a thoroughly prettied-up version of the Holland Handkerchief, but the song was collected later in Ireland.

Is there a scholarly edition of Child with all of that in, or has anyone written a Companion to Child...?