Janiah Fairburn, 20, and her 2-year-old daughter, Azarliyah Hadfield died after their people mover collided head-on with a silver sedan driven by the 19-year-old at Topuni on March 30.
Fairburn's partner, Henare Hadfield, suffered broken ribs and a punctured lung and is recovering at Auckland City Hospital.
Their 1-year-old son, Te Tairawhiti Hadfield, is being treated for spinal injuries at Starship hospital.
The defendant is facing two charges of driving with excess breath alcohol causing death, and another of failing to stop.
He allegedly had a breath alcohol level of 768mcg of alcohol per litre of breath at the time of the crash. There is a zero alcohol limit for motorists aged under 20, while the legal limit for those over 20 is 250mcg.
The man was unable to leave his hospital bed for his appearance in the North Shore District Court on Monday last week and was remanded in custody at Auckland City Hospital. He was granted interim name suppression.