Muchas Gracias for the response.
I won't try to write en español as I am certain that I would only butcher the attempt.
The information is useful and also correlates with some other assumptions that has been handed down in my family. As I have been told in the early missionary times it was not uncommon for the Spaniards who came to the Philippine shores to marry and take on local wives. This is in no small part responsible for the propagation of the Spanish lineage so common in the PI (Philippine Islands). The large number of Eraña's in the Baqsue region is also borne out by the fact that anyone I talked to from our Mechanica de la Peña office in Bilbao assumed that I was from the region (much to their surprise when we first met in person!)
It's good to know about the Casa de Contratación de Sevilla... That would be a good starting point for some research! Gracias!
Good wishes!
Miguel