Whanganui resident Zane Town, 14, and his mother 41 year-old Jenny Town were also killed in a crash.
Police are now looking to talk to the driver of a white van that was at the intersection at the time of the crash.
The deaths were among 10 on the roads over the weekend, prompting police's most senior road policing officer, Assistant Commissioner Dave Cliff, to suggest some rural roads might need lower speed limits.
But Mrs Redfearn's sister Auriol Hutchins, speaking from Queensland, said speed limits were irrelevant to the accident that claimed her sister's life.
"The same issue happens over here and I think the more rules they have - the more they restrict speed limits, the more cameras are out - the worse it's getting."
Ms Hutchins used to live in New Zealand and recalled terrible traffic on some rural highways. Bad driving, especially in short passing lanes, was a big problem.
She said lower speed limits would not stop people "doing stupid things, or taking risks" in unsafe locations.
Mrs Redfern was a mother, a grandmother, and one of six siblings in a blended family. Her family lived in Australia and New Zealand.
Her older brother Les White, who lives in Melbourne, was returning to New Zealand tomorrow to farewell his sister.
Mr White understood Mr Redfearn was recovering as well as could be hoped for.
"He was able to get out of the car on his own and go round the other side and talk to Judy, and arrange for a dog they had in the back to go with a friend back to Whanganui to their daughter's place."
He said it was a difficult time for Judy and Fred's relatives and friends. The Redfearns had retired in Palmerston North not long ago.
"They had just retired and sold their nursery and just shifted into town."
Mr White said it was hard to apportion blame or ascertain the cause of the crash, but it seemed speed was not a factor.
He said drivers needed better education and a cultural shift might even be necessary to reduce the level of reckless driving here.
"I think it's a lack of ability [that] kills more than anything."
He said he hoped the driver of the van did the right thing and came forward as requested.
It was hard for Mr White to know his younger sister was gone.
"You kind of think ... it should be me first. You know your parents are going because they get old and they get sick or something. But to have it just out of the blue like that, it's the one that really hurts."
Police were still looking for anybody who witnessed the fatal crash.
Around New Zealand, seven other people died after crashes in Clevedon, Te Puna, Warkworth and Christchurch.
Mr Cliff said the weekend's road toll was a "preventable tragedy".
He said it was also saddening to see so many people die right at the end of United Nations Road Safety Week, where police poured effort into educating people about preventing casualties among children around schools.
"Although these crashes don't involve that, just to lose so many people over such a short period is a real gut-wrenching thing for those people who are affected," Mr Cliff said.
