"I said to them 'I've got some news... and it's good news.' There was still a few 'oh my Gods' in response," she said.
The siblings started their syndicate a couple of years ago, buying $6 Lotto ticket each week using their own lucky numbers.
One sister, based in Hokitika, took the lead buying the ticket and checking their numbers.
They planned to use their share of the winnings to help save for retirement, home renovations and travel.
"We are all still working but retirement doesn't seem that far off, so we decided to have a go each week at winning the big one - after all it can happen to anybody," said the sister.
A Wellington couple have also claimed their $1 million first division Lotto prize prize, two weeks after the winning draw.
The couple, who bought their ticket in Upper Hutt, regularly play Lotto but got delayed checking their ticket during the summer break.