N.J. Stat. § 3B:12-30
The parents who have been appointed the guardian of an unmarried incapacitated person or the spouse or domestic partner as defined in section 3 of P.L. 2003, c. 246(C.26:8A-3) who has been appointed the guardian of an incapacitated person may, by will, appoint a testamentary guardian of the person, or a guardian of the estate, or of both the person and estate of the incapacitated person. Before the appointment of a testamentary guardian becomes effective, the person designated as the testamentary guardian shall apply to the court in a summary manner, upon notice to the incapacitated person, to any guardian who may have been appointed for the incapacitated person, to the person or institution having the care of the incapacitated person and to such heirs as the court may direct, for a judgment confirming that appointment under the will.
N.J.S. § 3B:12-30