Moses and Aaron shown to be the crown of the previous pedigrees. They gather the "heads" who are to speak to Pharaoh, Exodus 6:27.
Related Commentaries of Exodus 6:14
Exodus 6:14
14 These be the heads of their fathers' houses: The sons of Reuben the firstborn of Israel; Hanoch, and Pallu, Hezron, and Carmi: these be the families of Reuben.