Eu não acho que você encontrará muitos advogados aqui. Sua melhor aposta é ler a lei e tentar ficar o mais longe possível das linhas:
In the United States, the Copyright Act defines "derivative work" in 17 U.S.C. § 101:
A “derivative work” is a work based upon one or more preexisting works, such as a translation, musical arrangement, dramatization, fictionalization, motion picture version, sound recording, art reproduction, abridgment, condensation, or any other form in which a work may be recast, transformed, or adapted. A work consisting of editorial revisions, annotations, elaborations, or other modifications which, as a whole, represent an original work of authorship, is a “derivative work”.