Who was Zerach (seeing as he was not listed in Bereishis 46:10) among the sons of Shimon)?
Rashi: Which is like 'Tzohar'
Why does the Pasuk omit the family of Ohad that is mentioned in Bereishis 46:10?
Hadar Zekenim (1): Some of Yakov's grandsons had few descendants 3 , and those families became called on the names of their brothers who had large families, and were assimilated into them.
Rashi writes that seven families of the 70 became Batel. If so, why are 65 families listed here?
Peninim mi'Shulchan ha'Gra (Bereishis 46:8): The 70 who descended to Egypt included Yakov's 12 sons, Efrayim and Menasheh, and three females. None of them are called families here. Here, it lists 12 families from Efrayim and Menasheh, and an additional five from Levi. This would complete 70, but five families are missing - Ohad from Shimon, Gera, Becher and Rosh from Binyamin, 1 and Yishvah from Asher.
The Vilna Gaon does not count Binyamin's sons Na'aman and Ard among the lost families, for these two were replaced by new families with the same names (sons of Bela ben Binyamin). (PF)
Rashi writes 'I do not know the fourth missing family of Levi.' Nefeg and Zichri, Bnei Yitzhar, and missing!
Moshav Zekenim: Only Levi's sons and grandsons are called families. Nefeg and Zichri were his great grandsons; they are part of Yitzhar.