N.J. Stat. § 46:38-20
A person designated a successor custodian shall be deemed to have accepted the custodianship upon the execution by him and delivery to the person or court who designated him a notice in writing of his acceptance of the custodianship. If the successor designee does not deliver such a notice of acceptance to the designator within 10 days of delivery to him of the designation, the designator shall promptly deliver to the successor designee a notice in writing requesting an acceptance or renunciation. If the successor designee fails to deliver to the donor a written notice of acceptance or renunciation within 10 days after delivery to him of the request he shall be deemed to have renounced. In that event the donor shall make a written recital of the failure to respond and the consequent renunciation.
The designator shall promptly cause a copy of each writing sent, received or made by him to be delivered to the original custodian or his legal representative, to each other successor custodian, to the donor and to the minor if he is then 14 years of age or more.
N.J.S. § 46:38-20