If your house is 7 bedrooms and all around you are 3 bedrooms, there are adjustments they can make.
I would question their use of anything else; you have the right to do so.
Example-- one of my properties was a 2 bedroom condo in New Paltz, we found a buyer and an appraisal was ordered. The problem was that no TWO bedroom condos had been sold for over 1 year. He had to look to nearby Highland to find comparative sales. He also did evaluate some one bedroom units and gave credit for the second bedroom.