N.J. Stat. Ann. § 44:4-51

In case of the commitment or admission of a poor person or a member of his family, through the agency of the director of welfare under the supervision of the county welfare board, to an almshouse, welfare-house or other institution or family, the director shall file a copy of the record provided for in section 44:4-50 of this title, or a record of the admission or commitment, with the commissioner at his office at Trenton, and in case of an infant a copy thereof shall be within the same time filed with the state board of children's guardians at its office. Such filing within the time limited may be by registered mail.