N.Y. Comp. Codes R. & Regs. tit. 9, § 2104.5
(b) where the housing accommodations are located in a structure or premises which contain more than two housing accommodations and the housing accommodations or structure or premises are owned by two or more persons not constituting a cooperative corporation or association (husband and wife as owners being considered one owner for this purpose), no certificate shall be issued under this section for occupancy of any housing accommodation in such structure or premises where two housing accommodations are already owner-occupied as a result of certificates of eviction. The prohibition contained in this subdivision shall not apply where the co-owners stand in the relationship of immediate family as defined in subdivision (a) of this section.
(3) No certificate of eviction shall be issued under paragraph (1) of this subdivision, except as provided in paragraph (4) of this subdivision, unless the applicant shall also establish that the cooperative corporation or association has complied with the following requirements:
(5) As used herein, the term tenant-owner includes only:
(c)
(d) Where the landlord purchased and thereby acquired title to the premises on or after May 1, 1950, or where the landlord acquired his rights in the housing accommodations (other than in a structure or premises owned by a cooperative corporation or association) through an enforceable contract of sale of the real property which meets the minimum requirements of this subdivision, no certificate shall be issued under subdivisions (a), (b) or (c) of this section unless the landlord on or before the date of the filing of the application has made a payment or payments totaling at least 20 percent of the purchase price or the assessed valuation of the premises, whichever is greater; provided, however, that where the Administrator finds that equivalent accommodations are available for rent into which the tenant can move without substantial hardship or loss, or that undue hardship would result to the landlord, a certificate may be issued although less than 20 percent has been paid. This requirement shall not apply where the landlord is a former member of the Armed Forces of the United States of America who obtained a loan for use in purchasing housing accommodations guaranteed in whole or part by the Administrator of Veterans Affairs. The contract of sale of the real property referred to in this subdivision shall:
(a)