N.J. Stat. § 54:5-89.1
In any action to foreclose the right of redemption in any property sold for unpaid taxes or other municipal liens, all persons claiming an interest in or an encumbrance or lien upon such property, by or through any conveyance, mortgage, assignment, lien or any instrument which, by any provision of law, could be recorded, registered, entered or filed in any public office in this State, and which shall not be so recorded, registered, entered or filed at the time of the filing of the complaint in such action shall be bound by the proceedings in the action so far as such property is concerned, in the same manner as if the person had been made a party to and appeared in such action, and the judgment therein had been made against the person as one of the defendants therein; but such person, upon causing such conveyance, mortgage, assignment, lien, claim or other instrument to be recorded, registered, entered or filed as provided by law, may apply to be made a party to such action. No person, however, shall be admitted as a party to such action, nor shall the person have the right to redeem the lands from the tax sale whenever it shall appear that the person has acquired such interest in the lands for less than fair market value after the filing of the complaint, except where such transferee is related by blood or marriage to, or who, because of other close or personal relationship with the transferor, would in normal course be a party to an instrument for little or no consideration, or where such party acquired his interest at a judicial sale.
N.J.S. § 54:5-89.1