N.J. Stat. § 44:1-79
Contiguous or adjoining municipalities in a county may, through their governing bodies, agree in writing after resolution duly passed in each that the overseer of one or more of them may and shall act for and within one or more of them in lieu of the appointment of an overseer in the adjoining municipality so contracting, and thereupon such additional salary shall be paid the overseer as is agreed upon, with and not without his express consent in writing thereto. In such case the overseer shall have like authority and responsibilities as other overseers, and the overseer theretofore appointed in the municipality contracting for the other overseer shall upon notice to this effect to him cease to hold the office within thirty days after the agreement is executed.
N.J.S. § 44:1-79