Ash Thom last night confirmed her twin sister, Alanna Louise Thom (24), was the person killed when two cars collided near Waihola on New Year's Eve.
The crash happened on State Highway 1, just north of the township, about 1.30pm.
A man from the second vehicle remains in Dunedin Hospital after being taken there in a moderate condition with leg injuries following the crash.
Last night, Ms Thom said she and her family were ''just so deeply shocked and numb'' at the loss of their loved one.
''Our sister has gone and nothing will change that. Our hearts go out to the other passengers in the other car affected [by] the accident.''
Ms Thom said her twin sister was a ''free spirit'' who had been studying and working at the University Bookshop, while also planning a trip to Nepal.
''It's just so crazy to think she's gone,'' she said.
She had been returning from a trip to Wanaka, where she had been spending time with friends at the Wanaka camping ground, when the accident happened.
Initial information had been given to the family by police about the crash and more was expected to be released to them later today, Ms Thom said.
Her death has prompted a flood of death notices, and friends have also taken to social media to pay tribute to Alanna Thom, describing her as ''the brightest soul''.
''No words can describe this feeling,'' one said.
The road toll for the holiday period - which began at 4pm on Christmas Eve and ended at 6am today - was nine.
It also pushed New Zealand's total road toll for 2018 to 381, the highest it has been since 2009.
