New York Consolidated Laws, Multiple Dwelling Law - MDW § 162. Single ownership

The owner of any site or plot upon which a garden-type maisonette dwelling project is proposed to be erected shall execute and file in the office of the recording officer in the county where deeds of conveyances are recorded an instrument in writing which shall declare that, so long as any of the buildings proposed to be erected remain standing, a conveyance of any part or parts of such project shall, thereupon, cause all the buildings on such site or plot to be and become unlawful structures, and any prior certificate of occupancy issued for such structures shall thereupon become void.  Nothing in this section shall be deemed to prohibit the sale of any part of such project, provided, however, that the part which is so conveyed and the remaining part of the project shall be made to comply to all of the applicable provisions of this chapter.