Hi Juan,
It's nice to know another Sadaba. I know that there are a few Sadabas here in Southern California where I live, but not sure where they are from.
As for the Filipino Sadabas, more than likely they were given that surname since Filipinos in the beginning had no surnames. They had a book, Catologo Alfabetico de Apellidos that had thousands and thousands of names not just of Spanish origin but also Chinese and Filipino origins. As of yet, I don't know for sure if the Sadaba surname was taken on by an ancestor of mine or if he was really a Sadaba by blood. My guess is that the surname was chosen, not handed down.
Kalani