Looking for Cullen of New Zealand

I am looking for information about the family of a James Cullen (b. circa 1880),possibly in Scotland, who is believed to have emigrated to New Zealand at around the end of the 19th/ start of the 20th centuries. James was a brother of my grandmother Margaret Cullen. Margaret married my grandfather, James Rose MacGillivray in Hamilton in Scotland on 29/06/1900. Any information about James and his decendants would be very much appreciated.