Laura Langston (left) has been left in shock by the death of her twin Sophie.
Sophie Langston and her partner, Simon Thomas, weren't looking forward to their drive back to Auckland after a family funeral in Whanganui.
Many of the main roads had been closed because of the recent flooding and the couple were forced to make diversion after diversion.
But despite their caution, they were involved in a collision with another car just south of Turangi and Miss Langston, 28, was killed.
Mr Thomas, who was driving, was seriously injured and taken to Taupo Hospital.
Miss Langston, an Auckland florist, is survived by her twin, Laura, and half-sister, Nicky Sikora of New Plymouth.
Last night, Ms Sikora told the Herald the couple planned to drive cautiously home from her mother's funeral. "They said the drive [down] had been horrible ... they were going to go back real slow and careful."
Ms Sikora said Mr Thomas was recovering and was yesterday travelling back to Auckland. Friends and family were rallying around Laura, who had now lost all her immediate family - her father died eight years ago and their mother died of multiple sclerosis two years ago.
Ms Sikora, 48, said Laura still appeared to be in shock, busying herself by organising her twin's funeral in Auckland on Monday, which was expected to be huge. "Flowers will be a huge part and I think she would want her dog, Mischief, there too ... there will be a lot of young people too; they were real social girls."
Sophie and Mr Thomas had helped with the funeral of Ms Sikora's mother. Sophie did all the flowers while her partner looked after the music.
The trio had made stronger bonds over their past few days together, Ms Sikora said.
"It was so special because they were leaving and we had a hug, the three of us ... and we just said how much we loved each other and how special our time together had been."
Ms Sikora said she was reunited with her half-sisters after Laura approached TV programme Missing Pieces in 2012 to find their father.
The producers discovered he had passed away, but instead found Ms Sikora and her four children, Grace, 15, Rubi, 22, and twins Holly and Shea, who are the same age as Laura and Sophie, 28.
All the girls bonded instantly, she said. "We have since that day just been so close ... We're all quite extroverted, individual characters so it was just fun-chaos when we were together."
Mr Thomas' brother Chris has set up a Givealittle page to help Laura with the funeral costs. Last night, more than $28,800 had been raised.
Any extra will be used to help alleviate the debt incurred by medical bills for the treatment of their mother over the years.
• To donate: givealittle.co.nz/cause/forsophie
Police have concerns for the welfare of Tennessee and her children.