(d) where the vacant housing accommodations are combined, modified, divided or the dimension of such housing accommodation otherwise altered and these changes are being made pursuant to a preservation regulatory agreement with a federal, state or local governmental agency or instrumentality, the rent stabilized rents charged thereafter shall be based on an initial rent set by such agency or instrumentality.
(e) where an owner substantially decreases the outer dimensions of a vacant housing accommodation, such initial rent shall be the prior rent of such housing accommodation, decreased by the same percentage the square footage of the original apartment was decreased by and such other increases authorized by this chapter including any applicable guideline increase and individual apartment improvement increase that could be authorized for the apartment prior to the alteration of the outer dimensions.
(f) (i) when an owner combines two or more rent regulated apartments, the owner may use each of the previous apartments' remaining individual apartment improvement allowances for the purposes of a temporary individual apartment improvement rent increase. The owner shall subsequently designate a surviving apartment for the purposes of registration that has the same apartment number as one of the prior apartments. If that prior apartment has any reimbursable individual apartment improvement money remaining after the combination, that money may be reimbursed for future individual apartment improvements undertaken within the subsequent fifteen years following the combination.