It's been a long time since you posted this, but I happened on it today! I was helping someone with a search of the Oswald-Castro family. James Oswald was the son of Mary Gloria Castro and Alfred Oswald. Mary's mother was a Silva. Alfred had a sister Aurelia and a brother, Eddie. Their father Benjamin worked in the Almaden quicksilver mine, and died before 1900. He was born in Chile of a Scottish father. Very interesting family.
I don't have much to share yet, as I'm just beginning this research, but wanted to add this!