Francis Henry Goodwin- a genealogical conundrum

Ive been concentrating on my Goodwin branch lately. When looking for another relatives photo on the wonderful Auckland Libraries Heritage Images website , I came across the image above for Francis Henry and recalled the research I had done on him a little while ago.

I first came across Francis Henry when his name appeared in a list of casualties during World War I . He was listed as being from Ngaruawahia where much of my Goodwin family resided, and his next of kin is listed as Sarah Moffit (Aunt). Sarah Moffit was in fact Sarah Ann Goodwin (daughter of my 3x G Grandparents William Henry and Jane Goodwin) who had married Edward Moffit and lived in Ngaruawhahia. So Francis must have been the child of one of her Sarahs siblings--- but which one? His birth did not appear in the New Zealand births deaths and marriages register.  He was certainly old enough to appear there - I estimated he must have been born prior to 1896 to be eligible for service in WWI.
Francis, was serving in the Dardanelles when he went missing on June 6th 1915. The next record in his file is August 11th of the same year when he is admitted to the hospital with Enteritis and on the same date he is transferred to Cairo to the NZ hospital there. From there he is discharged as medically unfit when it is discovered that he is in fact underage. His attestation form gives a date of birth of 10 August 1894. Stating he was born in Newmarket Auckland.
His war record file is thick - it covers both his service in WWI and later in WWII, where surprisingly he still seems confused by his date of birth. He lists it as 10 August but the year is crossed out twice and eventually listed as 1898. This date seems more in line with his looks in the photo above, however was of no use in finding a birth or discovering who his parents were.
In 1919 Francis married Ada Hill. He lists his age as 21 which coincides with a birth date of 1898. At last - I could find out Francis’ parents , from his marriage certificate.

Francis’parents were Samuel Henry Goodwin and Lettie( Letitia) Goodwin nee Meekin. Samuel was in fact the younger brother of Sarah Ann Moffit as I had thought. Samuel was born in 1866 so was 8 years younger than his sister Sarah. Letitia Meekin was much younger than Samuel. Her date of birth is listed as 1882, and in 1898 when Francis was born, Samuel and Letitia were not married.
I suspect the fact that Letitia was under the age of 16 when Francis was born has a lot to do with why his birth was not registered, however it is interesting to note that Samuel and Letitia did in fact marry, 7 years later in 1905. They went on to have at least four more children together before Samuel died in 1926.
The interesting thing is during the period of World War I Samuel and Letitia were in fact living in Ngaruawahia as well. They were all a family at one point if this photo below is as described, a photo of Samuel and Letitia with Frank and his younger brother James Henry. Why did Francis not list his parents as his next of kin? Was he estranged from them? This part of the mystery will probably not ever be solved.