Rights management that deals with samples and licensing can get complicated, quickly. At this time, TuneRegistry does not offer a complete "Samples Management" solution. It's on our roadmap for future development.
If you're using samples in your track, you should not include the original artists in the Track Credits for your Recording and Release registrations. You can, however, include writers/publishers of the sample on the Song Details page if you have cleared the sample and negotiated publishing splits.