The first child from the union of New York Jewish patriarch Moses Raphael Levy and his second wife Grace Mears Levy, Rachel was born in London a year after her parents’ wedding. The three of them soon crossed the Atlantic, and upon arrival in New York, mother and daughter met for the first time their new step-children and half siblings, including Abigail Levy Franks. Though it proved difficult, sometimes futile, for Grace to win over these new relatives, Rachel was well loved throughout the family.

In 1740, Rachel married a Portuguese-born merchant who had, after some time spent in Bordeaux and then England, recently made the journey to New York—Isaac Mendes Seixas. The marriage evidently caused something of an uproar among the Sephardi old guard of New York’s Jewish community, who objected to Seixas’ taking an Ashkenazi wife. Abigail Franks, tireless observer of her world, not to mention a relentless gossip, recorded that Seixas’ uncle Rodrigo Pacheco was “displeased” by his nephew’s marriage to a German Jew, and furthermore, “the Portugueze here where in A Violent Uproar about hit for he Did not invite any of them to ye Wedding.”

It was not just the “mixed-marriage”—that transgression of contemporary ethnic and class barriers—that troubled some about the union. Abigail declared that Isaac had an “Untractable Dispossion.” However, after visiting with the young couple for a week at their new home in New Jersey, where Isaac opened a “Small Country Store,” Abigail characterized Isaac as “A person of his Temper Soe much Mended,” and that “they Seem to be very happy in each other.”

They would have eight children, including Gershom Mendes Seixas.