Our question is why do you want to convert from 2 to 1 family?
Usually demand and price increases from 1 to 2 family not the reverse, unless you have fewer bedrooms and baths than the other comparable homes in the neighborhood.
Before taking the plunge and expense for the conversion via a new C/O have you spoken to Realtors to determine the price differential (gain) to move forward?
If you were not selling and wanted to convert to a mother/daughter or hospitality suite for a relative, it is a good idea. However, you indicate you are selling. That's why it may make more sense to leave it a 2 family but move forward with the renovation. And when you renovate to sell, try to update simply and with features that appeal to most buyers. Re-doing kitchens and baths are always a good idea, and painting in light airy colors to open up rooms is excellent.
As full-time Brooklyn Realtors, we would be happy to assist you and include a free home evaluation. We hope this information is helpful to you, and please don't hesitate to call!
David Rogoff & Bonnie Chernin
Real Estate Sales Associates
Fillmore Real Estate - Branch 19
Brooklyn NY 11210
917-593-4068 - David mobile
646-318-5031 - Bonnie mobile