The In Laws in question are those of Charles Anderson and his son, WD.
Charles' wife, Rebecca, was a Finlayson from the north west of Scotland.
Rebecca's mother's family were the Grays, also from the north west of Scotland.
WD's wife, Peggy, was a first generation New Zealander. Her father's family were the Brewsters from County Londonderry, Northern Ireland.
Peggy's mother's family were the Grays, also from Londonderry.
Many others of these families also migrated to New Zealand. In fact, there were a great number of them, very few of whom I knew or had heard of prior to researching my ancestry.