Thanks for the answer. But I would need the Playlist container to play 1 of each group simultaneously, since they are seperate stems of the same soundtrack. A solution would be to have a random container inside the Music Segment. So you would have:
Switch Container -> Playlist Container (eg. Section 1 of 4) -> Music Segment -> Random Container -> Two Melody tracks.
The system would then choose one of the melodies and play them along with the rest of the stems located in the Music Segment.