"She's my little angel now and I'll make the most of every day with her."
Mr Brown said Elyse knew her mum, Leonie Angela Berger, and big brother Leroy, 9, were dead, but the gravity of the situation had not sunk in for her yet.
"She's clearing her head. It's hard, eh, at that age. I don't think she really realises.
"We just said they've gone to heaven and she said, 'Why can't I?' I think she might want to visit them - it's very hard for her to take everything in."
The Warkworth youngster survived the crash with moderate injuries and is recovering in the Starship hospital in Auckland.
She is improving every day, her dad said, and today managed to eat and drink for the first time.
All going well, she should be released in about four days, as long as tests on her hearing and memory come back with positive results.
Mr Brown said Elyse was quiet by nature, just as her brother had been - he said his children took after him in that regard.
Elyse and Leroy were close and she used to follow him everywhere, Mr Brown said.
"She's lost her little mate. Whatever he did, she would go along."
Mr Brown didn't think Elyse would ever get over the loss of her mum and big brother, but he would try to talk about them with her when he thought she was ready.
"Just when she wants to, eh? Maybe if we go out for a bike ride and I'll say to her, you know, Leroy is still with us."
It was his mission to keep his daughter positive, Mr Brown said.
"I just said to her you're a very lucky little girl and you're strong and you're keeping everyone else strong. Everyone can't believe you're here."
Elyse's friends have visited her in hospital and at Warkworth Primary School, where Elyse and Leroy were both pupils, collages and murals for Leroy have been hung on the walls.
Mr Brown said he was trying to keep busy, and especially to keep his mind busy, and funeral preparations were keeping him occupied for the moment.
"I haven't had any time - just busy from when I wake up till when I go to bed."
He said dealing with the loss of his son and his former partner had given him empathy for the families of other road accident victims, and he thought the road toll in New Zealand was too high.
"I don't know what the answer is; it's just getting worse and worse.
"I just feel for everyone else and wonder what they've been through."
Already this year 65 people have died on New Zealand roads, 17 in the past week alone.
In the first two months of last year, 55 people died, and 41 died in that time in 2014.
