N.J. Ct. R. 5:12-2

(a) Summons or Order to Show Cause. Process shall be by Summons or Order to Show Cause served in accordance with R. 4:4-4 no less than ten days prior to the return day therein or such other times as the court may fix or as otherwise required by law.

(b) Affidavits. Where it appears to the court by Affidavit of Diligent Inquiry filed in the action that any proper party, including a legal or putative parent, cannot be located, the court shall assume jurisdiction and proceed to summarily hear the matter. Prior thereto inquiry shall have been made of the nearest relatives of said party, and if such inquiry is unsuccessful, then of all persons known to be connected with the said party by marriage or in business, or of all persons whom the person making the inquiry has reason to believe, possess knowledge of the residence or post office address of the party. The inquiry may be made in person or letter, enclosing postage for the return of an answer, and shall describe the nature of the action that has been or is about to be commenced, and that the object of the inquiry is to give the party notice of such action and that the party may appear and be heard. The person who has made the inquiry shall file an affidavit setting forth the nature of the inquiry and its result, fully specifying the inquiry made, of what persons and in what manner, so that by the facts therein it may appear that the inquiry was made in good faith and for the purpose of effecting actual notice to the party; if the affidavit shall disclose that the inquiry has elicited information of the residence or post office address of the party, it shall state why personal service of process cannot be made and be accompanied by an affidavit of the person furnishing such information, disclosing the affiant's knowledge of such residence or post office address, if such affidavit can be obtained. If it appears that the party resides outside the state and process has been served within this state, an affidavit must be filed stating the circumstances under which the party was served. The court in its discretion and having due regard for the expeditious disposition of the matter, may require such additional inquiries as it believes may be fruitful and serve the interest of justice.