It seems to be a ?????? what the relationship was between Rochel and Leah – the Seder Oilam (I think) says they were paternally related but maternally not.
I know, however, that the ????”? brings a ???? that they were twins – because ??? in ??????? learns from ??? that one must not marry a younger sister before an older sister. The ????”? asks – why do we learn from ???s trick – we should learn that it is allowed from the fact that ???? was willing to do it!?
He answers that ???? agreed that one would not be allowed to marry a younger sister before the older sister. However, ???? was going ?????? that the younger twin is older than the older twin, because ??”? says in ???? ?????? that when you have a container, the first thing out is the last one in. Therefore, ???? married ??? because she was a younger twin.