Who was Yashuv (who was not mentioned in Vayigash among those who went down to Egypt)?
Seeing as, with the exception of Efrayim and Menasheh, only the grandsons of Ya'akov who were already born when they went down to Egypt were counted as separate families, why are Ard and Na'aman, sons of Bela ben Binyamin, listed here as families?
Rashi #2: Bela had many children and grandchildren, all of whom were considered part of his family, with the exception of Ard and Na'aman, who had many offspring of their own, and who are therefore listed as independent families. 4
Ramban #1: Ard and Na'aman sons of Binyamin, died without children, and Bela, wanting to perpetuate his brothers' names, called his sons after them, 5 and that is why they were counted as independent families.
Ramban #3: In spite of the seventy families that went down to Egypt, it was customary to divide large families into smaller family groups and to appoint a head over each segment. 8 And that explains why many of those listed here were not listed in Vayigash
See Ramban, DH 'va'Ani Tamah alav '.
The namesakes of their uncles (Binyamin's sons).
In which case they were twins.
Rashi: And the same applies to Menasheh's son Machir, whose son Gil'ad had many offspring of his own and who is therefore listed as an independent family.
Ramban: Perhaps even by means of Yibum