Yosi, the church Santo Tomas de Janico has many records dating back to the mid to early 19th century, so I'm pretty sure you can find A lot about your family three. Also, the most famous genealogist in DR, and my Tocallo Edwin Espinal Hernandez is from Janico, so if you can some how get in contact with him, maybe he can help you out. In my case one of the genealogust in the Instituto de Genealogia Dominicano helped me with my family three.
Anyways, also check out the link posted by alterEgo, there's lot of info, and someone there posted a link to the familysearch site which can help you with your research.