WJRankin on Family Tree Circles

I Have been tracing my family tree, mainly the Rankin`s and Scobies in the Gore ,Dunedin area of New Zealand for over a year ,and i would like some help with some information about Ernest Black(1898-1973) who married my great Aunt ,Marjorie Catherine McKenzie Rankin(1902-1967) in 1926 waikaka,Southland, New Zealand.Ernest may have had 2 brothers,Oliver & Samuel.
Can anyone help with information on where they originated from ,linerage ,arrival in NZ .ect