The State Archives has early land records 1679-1769. First counties were formed in 1769 and land records are found in the counties after that date. Check the State Archives for printed indexes. New Jersey is unique among the 13 colonies in that its proprietors retained their rights after the Revolution to grant lands and receive back escheated land. They still retain these rights.
Proprietary shares pass down the generations by inheritance and purchase like other property.
Most have been microfilmed and are now in the State Archives. Deeds after 1785 are found in the counties. 32 boxes of Alexander papers are found in the New York Historical Society. Similar papers are located at the PA archives in Philadelphia. It is suggested that the state archives be the first stop for this state.