Family - including Phillipa Morehu, the girls' mother - had visited the driver in hospital before he was interviewed and subsequently charged by police.
"Everyone that's involved and their family have all been to see him, even the mother of the two girls," his father said. "I did ask him if he didn't want to go [to] the tangi but he said that's okay, he wanted to go to the funeral."
His son had injured his hip in the crash and had also been left with "a bit of a hole" in his left leg.
"He was okay, he didn't mind talking about it," his father said.
He was close to his cousins, whom he was visiting for Christmas with family in Tauranga.
"He's got to live with it for the rest of his life, I suppose."
Two crosses bearing the girls' names have been erected near where they died.
The car in which they were travelling allegedly sped past another vehicle and slammed into a Mitsubishi ute and rolled on to its roof.
The two girls were on their way to visit their grandmother's grave at Tahuwhakatiki Cemetery when they were killed.
"It was a nice day until we each went our different ways," said their father, Wiremu Clark.
He said his daughters were not wearing seat belts and he warned other motorists to "just drive safe".
"It's time to buckle up. Our children are the best things you can ever have, and I've lost two," Mr Clark said.
The driver of the ute, Brett McCready, was also visiting family in Tauranga. He suffered minor injuries. He was recovering with family.
Police wish to speak with anyone who may have seen the Honda, a black Mitsubishi Lancer and another blue Honda, travelling in Orion Drive, Waikite Rd and Welcome Bay Rd between 3.30pm and 4.30pm on Christmas Day.
