Why are Naftoli's sons taught, but no one who descended from them?
'Rashi' citing Yerushalmi, Sof Megilah: Ezra found three Seforim of lineage. He wrote only what he found written. This Sefer skips 1 , for he skipped from copying from one Sefer to another. What he could not write here, he wrote in Sefer Ezra.
Redak (1): Perhaps Ezra did not find their lineage written, and he had no tradition of it 2 .
Malbim (1): The Sefer of lineage of Dan, Zevulun and Naftoli was lost via Galus.
Why does it say "Bnei Bilhah"?
Redak: This is for her praise - she willingly married Yakov. It says about her "va'Titen"; regarding Zilpah, it says [also] "va'Tikach 1 ".
Malbim: This includes Dan. Also Dan, Ezra did not find his [descendants'] lineage [so he omitted them].
Malbim citing Meforshim: Chushim is Ben Dan. Dan is called Acher, because he always went after (at the end) of the camps - "veha'Me'asef Holech Acharei ha'Aron." His Berachah was "ha'Noshech Ikvei Sus va'Yipol Rochevo Achor" - it bites the hind legs. Chushim and Bnei Naftoli are Bnei Bilhah.
I.e. Leah had to force her to marry Yakov. (PF)
