If you duplex performs better then market, you will get some money added to your appraisal, but comparative sales by enlarge will determine your sale price. 

CLICK on the image to enlarge.

I’ll do this comparison.By the property being “big enough” I meant that the yards are sizable all around, the house footprint could be enlarged without sacrificing much yard space.

Could use one of them to enlarge the existing other one.

It's a drop-in sink, so you might be able to pull it up, enlarge the cutout, and put in a bigger sink, but I wouldn't bother at that price point.

Right now is a time of transition: Click on Image to Enlarge Mortgage Applications Plummet To 18-Year Lows As Rates Hit 2010 HighsPerhaps a better solution is to utilize Seller Financing of some sort.

CLICK on Image to Enlarge.

Major kitchen renovation - took down 2 walls and completely changed the layout/opened it to other areasMaster bathroom - enlarged shower and complete gut, changed location of toilet to add space in master bath2nd bathroom - new floor, cabinet, fixtures, refinished wall tile for new looklaundry room - finished the walls and added floor tilePaint inside and outNew trim and door hardwareWhat was the outcome?

And you'll have new cracks in unexpected places, old cracks that will not close, but instead enlarge. 

I paid $960k for a 5 bedroom 3 bathroom ~5,000 SF home (dated) on a gorgeous 2 acres including gorgeous grounds, a quick walk to the nearest Festival entrance, and 40 or so minutes to Palm Springs.After $280k or so in remodeling the home (including adding 4 additional bathrooms), and $30k or so on enlarging the pool and improving the already impressive grounds (plus perhaps $30k in furnishings), we are grossing more then $400k a year in gross vacation rents.