1)
It says that Rachel and Leah gave Bilhah and Zilpah "l'Ishah", and the latter are called (Bereishis 37:2) "Neshei" (wives of Yakov). Why does it say (Bereishis 35:22) that Reuven lied with "Bilhah Pilegesh Aviv"?
1.
Bechor Shor (9): Yakov married them with Kesuvah and Kidushin. 1 When Reuven lied with her, he profaned her, and she is called a concubine.
1
From when they married Yakov, Rachel and Leah did not make them work. We find that they had their own tents (Bereishis 31:33). They are called "Shtei ha'Amahos" because initially they were slaves.
