In addition, you should reach out to an appraiser and to the management company of the units. The simple answer is the appraiser would take the "As Completed" value of the square footage, property characteristics, and location of the newly combined apartment and comp against similar properties in the building or the area. There are a few more nuances to it but that's the "quick and dirty" of it. I recently did a loan for two combined units in Scarsdale and again, without too many specifics, that is how the deal was done. Masha is correct in that with the complete deal picture, I could give a more specific answer.
If I can be of any further assistance, please feel free to reach out.
Senior Loan Officer
(718) 215-4069 (office)