A branch of the Diaz family in the Marianas is known as the Familian Gayego.
"Gallego" in Spanish means "someone from Galicia." Galicia is a region of Spain, famous for the shrine in Compostela to Saint James (Santiago), its cooking and the many Galicians who took to the high seas. Cuban dictator Fidel Castro's paternal roots are Galician. Famous actor Martin Sheen's real last name is Estevez and his father was born in Galicia, Spain.
"Gallego" is also a last name, just like in English there are people who are ethnically French, Fleming or Turk but there are also people with the last name French, Fleming or Turk.
Once again, it is a mystery why a Chamorro family should have Gayego as a family nickname. Did this Diaz family originate in the Marianas from a Galician named Diaz who settled on Guam? Was there a Chamorro Diaz who was given Gayego as a nickname for some unknown reason?
THE REGION OF GALICIA IN SPAIN