Her parents, three of her brothers, an aunty, cousin and other family members - including a baby - were travelling in the van when it collided with a refrigerated goods truck, just south of Picton on Sunday morning.
"It is a real shock because of the tragedy of our family," she said.
The family were heading home after the funeral, travelling to catch the ferry when the crash happened.
Princess is now at Wellington Hospital, where two of her brothers are in intensive care.
"They need support from us right now, especially in this hard time, because the partner and the daughter is gone and my mum and my aunty, all of them are gone," she said.
"It's very hard for my older brothers and my younger brothers also, who are in grief right now."
Police say the circumstances of the crash are still under investigation.
Marlborough Area Commander Simon Feltham said both vehicles had been seized for examination.
The probe will reveal if either vehicle had a dashcam containing footage of the crash that could reveal what happened.
Waka Kotahi said in the past decade there had been five fatalities and 21 serious injuries on State Highway 1 between Picton and Blenheim.
It was assisting the Serious Crash Unit with its investigation.
"We'll also carry out our own review of the crash site as we do in response to all fatal crashes on the state highway network and we'll focus on the potential contribution of any road or roadside factors to the crash and any safety improvements that can be made at this site," a spokesperson said.
The crash happened on the same bend where Picton man Gary Kenny died in a head-on collision with a truck in March 2020.
Road safety campaigner Clive Matthew-Wilson said the multiple-fatality crash was devastating and highlighted the need for a median barrier on the highway.
"Cars can't have head-on collisions when they're either side of the median barrier, it's really that simple," he said.
"The road to Picton is an accident waiting to happen. It's a 1950s road, basically. It's very narrow with a lot of cars in a hurry and a lot of tired drivers and it's sort of set-up for this sort of fatality."
Matthew-Wilson, editor of car website The Dog and Lemon Guide, said the government needed to rethink its focus around lowering speed limits.
In Picton, many locals told RNZ they did not think the road needed any improvements. But Laurie Stevenson, who travelled that stretch of road twice a day, said the state highway could do with more investment.
He said news of the crash was horrendous and came as a shock.
"The amount of traffic that it has, especially the ferry traffic several times a day, the road is definitely not up to standard. If this was the main road out of Auckland it would be at least four lanes."
He would like to see the road widened or the speed reduced to prevent further fatalities.
Two of the boys involved in the crash were students at Pukekohe High School. One of the boys was killed and his brother is in a serious condition in hospital.
School principal, Richard Barnett, said staff and students had been deeply affected by the tragedy.
"Everyone that I've spoken to that knew that family said what a lovely family they are. Obviously we hope that the one student who's very badly injured by that accident - we hope and pray he will recover."
Barnett said students had been offered grief counselling.