This may be the same family, as a process of elimination of all the other NZ born Olsens rules out the others.
"I remember Olsens living in Fabians Road in the 1950s. Their children were Stuart, Shirley and Lorraine plus one other son whose name I can't remember. ...
Much later the same Mrs Olsen lived in Moroa Plains Road, also known as Moroa road. Both addresses are rural Greytown
Russell Calvert (formerly of Fabians Road)." Cobblestones Museum, Greytown.