Nicole (16) was eighth in the senior women's artistic gymnastics level seven competition. She then qualified for the vault final and won bronze.
It was Nicole's first nationals medal and the first senior women's medal won by an Aorangi gymnast for many years. Stacey (13) won bronze in the 13-14 years trampoline and was fourth in the double mini trampoline.
Another Oamaru gymnast, Tessa Newton, from the Pathfinders Gymnastics Club, was 43rd of 70 competitors in the junior women's level four competition. It was her first national championships.
Nicole, a member of the Waimate Gymnastics Club, travels to Waimate three days a week to train, while Stacey is a member of the Saints Trampoline Club.
The other medal from the 11-strong Aorangi squad came from Sam Keenan, of Waimate, who won gold in the level seven pommel in the men's artistic gymnastics.
The team performed above expectations, manager Mark Herron said.