Dora Bas Rivka Silver O'H
Two Wives, Two Concubines and Eight Sons (So Far)
Yaakov had fallen in love with Rachel and he offered to work for Lavan for seven years in exchange for her hand in marriage. (Yaakov was well aware of Lavan's reputation as a trickster, so he specified that he intended to marry Lavan's younger daughter. This was meant to preclude Lavan bringing in another girl named Rachel or changing his daughter's names. As we shall see, it didn't help.) Lavan agreed to the terms, so Yaakov worked seven years. He loved Rachel so much that the time just flew by.
At the end of seven years, Yaakov asked for his wages, i.e., to marry Rachel. Lavan threw a wedding feast but at the last minute, he substituted Leah for Rachel. In the morning, Yaakov saw that he had been tricked and he wasn't too happy about it. When he confronted his uncle about it, Lavan just replied, "I don't know about where you come from, but in these parts the younger sister never gets married before the older one!" Lavan offered Yaakov a compromise: after the week of sheva brachos for Leah, he could then marry Rachel - and work another seven years to "pay" for the privilege! Yaakov didn't have much choice, seeing as he loved Rachel and was already legally wed to Leah.
And so, Yaakov ended up married to both Rachel and Leah, each of whom had a handmaiden. (Rachel's was named Bilha and Leah's was named Zilpah.) Yaakov loved Rachel more than he did Leah. This obviously hurt Leah, so G-d compensated her for her trouble by giving her children. Leah named her first son Reuven (Reuben), meaning that G-d saw her suffering and gave her a son in order to endear her to Yaakov. She named her second son Shimon (Simeon), meaning that G-d heard her despair and replied. She named her third son Levi, meaning that he should cause Yaakov to feel more connected to her. Her fourth son was named Yehudah (Judah), signifying thanks to G-d.
Rachel was devastated that her sister had borne four sons while she was still childless. She berated her husband who said, "What do you want from me? It's not my fault!" Rachel gave Yaakov her handmaiden Bilha as a surrogate. Bilha had a son, whom Rachel named Dan, meaning that G-d had judged the situation and answered her prayer. Bilha had a second son, whom Rachel named Naftali, meaning that she had been twisted around by her sister, Leah.
Meanwhile, Leah realized that she was no longer conceiving, so she sent Zilpah to serve as her surrogate with Yaakov. Zilpah had a son, whom Leah named Gad, meaning good fortune. Zilpah had a second son, whom Leah named Asher, reflecting her happiness.
One issue still needs resolution: how could Yaakov marry two sisters? (Actually, the situation is not really inherently problematic. It's only a question according to the Midrashic tradition that the Forefathers voluntarily kept the entire Torah before it was actually commanded to Israel.) Many answers are given. Just a few among these include:
*The Forefathers only kept the entire Torah in the Holy Land; Yaakov married sisters outside of Israel and Rachel died before they could all return there together.
*Rachel and Leah were only half-sisters from their father and not defined as sisters for this purpose (at least under Noachide Law).
*As converts, the family ties of birth were severed, so Rachel and Leah, while biologically sisters, were not sisters from a legal standpoint.
*Yaakov had already committed to marrying Rachel (or had already betrothed her); this obligation overrode his fulfillment of mitzvos, which was voluntary.
Other explanations are offered, but the bottom line is that if Yaakov did keep the entire Torah before it was given, he did so voluntarily and could make exceptions if he so desired.