Personal Opinion

Jessica is a comlicated character, she is Jew but betrays her father, Shylock, and leaves him ends up in Portia's household. Jessica is same as Portia, which means they are considered as the properties of their fathers, but the different point is, Portia obeys the order and gets a happy life; Jessica betrays Shylock, ironically, she gets a happy ever after, too.

Jessica's role in the story tells that only abandoning Jewish identity can she get a better life, which in order to emphasize Shylock's incorrectness and position.