1)
Why does it say "Bnei Yashan"? Only one is listed!
1.
Rashi (39): Perhaps there were another two or three [not named, to complete the count of 37 in verse 39].
2.
Radak: We find like this - "u'Vnei Falu Eli'av" (Bamidbar 26:8), "u'Vnei Chushim Dan" (Bereishis 46:23).
