For example, the Kate Bush song "In Search of Peter Pan" contains an excerpt from "When You Wish Upon a Star". As far as I can see, there's no way to represent that. "Based on" isn't really relevant. I could add a "Partial Recording" at the recording level, but I think it should be a work level relationship.
Do you think it would be worthwhile to create a new Work->Work relationship "Contains excerpt of"/"Is excerpted in"?