I see a lot of Spanish-speakers, particularly Latin American politicians, with multiple names. Which one should be used if you’re only using one name? Sometimes it seems like you can get away with only the first of the family names, e.g. Fernando Belaunde Terry can be referred to simply as “Belaunde” but not as “Terry”. Sometimes it seems like several are necessary - Javier Perez de Cuellar is often referred to as “Perez de Cuellar” but I’ve never seen “Perez” or “de Cuellar” standing on its own.
Is the first family name always the second name? I mean, could the second name actually be a middle name or part of a paired first name, which would mean you’d refer to the person by their third name?
the answer is here.