(4) if the documentation set forth in paragraphs (1) through (3) of this subdivision is not available or is inappropriate, data compiled by the DHCR, using sampling methods determined by the DHCR, for regulated housing accommodations.
However, in the absence of collusion or any relationship between an owner and any prior owner, where such owner purchases the housing accommodations upon a judicial sale, or such other sale effected in connection with, or to resolve, in whole or in part, a bankruptcy proceeding, mortgage foreclosure action or other judicial proceeding, and no records sufficient to establish the legal regulated rent were made available to such purchaser, such orders shall establish the legal regulated rent on the date of the inception of the complaining tenant's tenancy, or the date four years prior to the date of the filing of an overcharge complaint pursuant to this section, whichever is most recent, based on either:
(1) documented rents for comparable housing accommodations, whether or not subject to regulation pursuant to this Part, submitted by the owner, subject to rebuttal by the tenant; or
(2) if the documentation set forth in paragraph (1) of this subdivision is not available or is inappropriate, data compiled by the DHCR, using sampling methods determined by the DHCR, for regulated housing accommodations; or
(3) in the event that the information described in both paragraphs (1) and (2) of this subdivision is not available, the complaining tenant's rent reduced by the most recent guidelines adjustment.
This subdivision shall also apply where the owner purchases the housing accommodations subsequent to such judicial or other sale.