Why does the Torah omit Timna (who is mentioned in Divrei Hayamim I 1:36) from the sons of Elifaz, and why does the Torah mention Korach among the chieftains of Elifaz in 36:16, but not here among his sons?
Peninim mi'Shulchan ha'Gra: The Torah does, in fact, mention Timna - in that the word "ve'Timna" in 36:12 refers also to the sons of Elifaz in 36:11 (as if it had written "ve'Timna" twice). 1 However, when Elifaz took Timna as a concubine, he changed his son Timna's name to Korach - which explains why his name, and not that of Timna, appears among the chieftains.
Compare to Midrash Sechel Tov; refer to 36:12:2:4*.
There was seemingly no need to say "va'Yihyu" in this verse? (The same question may be asked on the word 'Hayu' regarding Bnei Bosmas, and regarding Bnei Aholivamah (36:13,14)!
Ha'amek Davar: This teaches that they were together a short time; afterwards, the descendants from different mothers settled in different places. Even when they were six in all, they were called Nefashos (plural; refer to 36:6:2:1).
