Information on My G Uncle and Aunty Frederick Edward and Paretahi Millar Burnell

I am looking for information on the family of Frederick Edward Burnell, Birthdate unknown but around the 1900s. Frederick married my Nanas sister Paretahi Millar in 1927 NZBDM: 1927/4211. Frederick died in Taumaranui, New Zealand in 1970 NZBDM: 1970/40480.
I have information on Paretahis siblings but nothing on any children of Frederick and Paretahi or if they had any. Paretahis Birth Registration was made in 1930 at the same time as her 5 siblings and we dont know why.