Hola!
I've been working on an interesting case (from a WD standpoint, not musically ;-) ), the song 19 by Paul Hardcastle. This became a massive hit in 1985, and was in large part based on samples of dialogue from the documentary film Vietnam Requiem. As a result the director and screenwriter of that film were awarded CA (composer/Author) credits by an American court. To add insult to injury, Mike Oldfield then claimed the song plagiarized parts of his original composition Tubular Bells, Pt. 1 and again Hardcastle lost out.
In order to model this I have created legal credit and sample credit, but it still feels a little wonky and I'm not quite sure what should go where. What I'm looking for is someone to critique it, do you have the time?