Hetty's aunt Sylvia Ann Howland also died in 1865, soon after her father. In September 1863, Sylvia Howland had willed half of her $2 million estate () to charities and entities in the town of New Bedford; the rest would be in a trust for Hetty, but once again without her control of the principal. By December, Hetty challenged the will's validity in court by producing an earlier will, made in January 1862, that left the entire estate to Hetty, and included a clause invalidating any subsequent wills. The will was challenged in court and the case, "Robinson v. Mandell", which is notable as an early example of the forensic use of mathematics, was ultimately decided against Robinson after the court ruled that the clause invalidating future wills, and Sylvia's signature to it, were forgeries. After five years of legal battles, Hetty was awarded a settlement of $600,000 ().