Familia Alteña-Franco de Paredes, Pérez y Franco, Pérez de Paredes

I came across a board on genealogy.com and other webpages from google that say these three families are somehow related but never mention exactly how. I do know that Pérez y Franco and Pérez de Paredes are related becuase the couple of Silão, Gto. in the 1600's had three sons two were given Pérez y Franco and the other Pérez de Paredes. Any Help? -Daniel MDC