First off, labels dont own publishing. The major publishing houses do. Some of those major publishing houses are divisions attached to the parent labels. 2nd, artists make side deals? HUH? WHAT? Where do you get this BS from?
Artists owning melodies? HAHAHA! Wtf are you on today?
"Sometimes a hip hop producer will have to replay the sample(not use it, replay it)" My genius friend, an interpolation is the sample re-played to variation. FML.
You have to actually BE in the music industry to actually know wtf you're talking about. Reading copyright laws off Google is a terrible way to gather facts in an industry where there are no rules and the "policies" change daily when whoever is in position of power simply decides to do so.