Hmm, not so sure this is the same John Gallie - you might be thinking of a Major in the American Civil War? You are correct that their father's name was John though. I wonder if it is this guy?: John Gallie - he was born 1854 so could even have been their grandfather. According to this site Oscar was born in Dunedin. The boys' uncle was Major A.R. Hislop of Wellington.