Lesley Elliott, her husband Gil and son Chris will all speak in court about how their loss has affected them as Ms Elliott's killer, Clayton Weatherston (33), is due to be sentenced in the High Court at Christchurch on Tuesday.
Weatherston, who stabbed and cut his former girlfriend 216 times, became the target of outrage after showing no remorse and boasting of his own achievements at his murder trial in July.
A jury rejected his defence that he was provoked into killing Ms Elliott (22).
Mrs Elliott said she did not like the thought of being back in a courtroom again after the month-long trial, but "from my point of view, anyway, I have to say these things for Sophie".
"It's all part of, I suppose, the grief process, you might say, in that we need to have our say.
And while probably what we actually say, and what we would like to say, might be slightly separated, I think probably we will get over the message."
The family's statements were not aimed at Weatherston.
"He's a nonentity as far as I'm concerned," Mrs Elliott said.
"If you've seen him, you know what he's like. I don't think anything will make much difference. But maybe it will make us feel a little bit better. Maybe one day he will wake up. I don't know."
Weatherston could face a lengthy minimum term of imprisonment, but Mrs Elliott said she was not personally too worried about it.
Getting a murder conviction was the main thing.
"Obviously, I think that punishment has to be punishment. Little kids, they do something wrong, they get punished. And big kids are the same, especially arrogant ones.
"If it's a good, long non-parole period, maybe 20-plus years, I think we will probably be reasonably satisfied."
Mrs Elliott said her family desperately needed to put the long saga behind them.
"I think from our point of view we need ... people use the word 'closure'. I don't like the word, but it's probably the best description, really. I think we just need to move on so that we can think about Sophie and not think about all that other stuff as well."
