In Spanish-speaking South America, if I recall rightly, both sons and daughters taken their parents' names in the same order. So if Price is the father, both would be Price de Jones. This seems like the mother's surname wins out, but when they are abbreviated, it's to Price.

Good question on the two hyphenated people, Zed. I've often wondered that myself! I don't know anyone in those circumstances, can anyone here help out?