Hi, I am trying to help a friend out and have gotten as far as I can so hoping someone can help. Two adults, one 11-year old, want to go:

July 25 JFK-SJU (San Juan, Puerto Rico)
Aug 3 SJU-SDQ (Santo Domingo, Dom. Republic)
Aug 10 SDQ-JFK

I have checked many scenarios and the best I could come up with is TWA, $1569 from travelocity.com. I checked expedia.com, 11thhourtravel.com, aa.com, united.com, itasoftware.com, lastminutedeals.com, cheaptickets.com and so on. I tried as two roundtrips (JFK-SJU, and SJU-SDQ) as well as three one-ways, and a multi-leg flight. Any help would be greatly appreciated! (I only know about going to Cozumel/Cancun and of course domestic US flights.)