This is another search that has led to numerous dead ends since it started in 2004. It was only after a fresh look by Anne that all the threads came together.
The soldier we were researching was 43120 Trooper Ernest Griffin NZEF.
Ernest was born in Liverpool, UK in 1888. He was a carpenter by trade. When he enlisted in New Zealand both his parents were dead and his sister Gertrude was listed as his NOK. Ernest married Isobel Kerby in 1920, however, they didn't have any children. Isobel died in 1925 and Ernest in 1970.
Of Ernest's siblings we know that:
Gertrude Evelyn Griffin, his sister and NOK, arrived NZ 1912, never married and died in 1965.
Ivy, another sister came with sister Gertrude to NZ in 1912. Ivy married Leslie Gilder Harden in 1915 and had two children.
Sydney Edward Griffin, his brother, never married, died in 1958.
Harry Percy Vivian Griffin, another brother, arrived NZ 1915, married, had no known children and died in 1970.
Wilfred Victor Griffin, Ernest's brother also served during WW1 with the NZEF.
Finally, another brother, Joseph Claude Griffin, died 1940 Liverpool UK
Anne followed Ivy's family and found the following through this line that she was able to contact Alexandra the great granddaughter of Ivy.
Well done Anne and thanks to Dan D who originally sent me the medal.
The returned medal tally is now 1862