That is very interesting!
Well, I was born in Argentina. In Latin America, the standard is upon marriage, men's surname remains the same, whereas women's add "de" plus husband's surname. So they keep their single surname, but have to add their husband's at the end. This is gradually, but unofficially, changing especially in the most culturally liberal countries in the region (Argentina being the craziest one in that respect) to just both keeping their surnames. Legally, it's still the other way. On the other hand, children traditionally get their father's surname only, but it's legally allowed to use the mother's name or both. In the past, everybody would go for the father's name, but now, without anything legal to stop it happening, the most common thing is to get both surnames, father's first. I'm personally in favour of just using the best sounding surname of combination thereof possible
I am not married, but my girlfriend (who is Peruvian) is OK with any of these combinations. In her country, adopting both father's and mother's surnames has been the most common thing for a long time.
By the way, my name is Lucas. "Cas" is just the "second half" of it. Very simple
