Mr Duncan was treated at Tauranga Hospital for serious facial wounds and a damaged collarbone.
During the melee Drewry tackled Stephen Peters, an associate of Mr Duncan's sons, to the ground.
Ake, Drewry and their associates only backed off when one of Mr Duncan's loaded a shotgun and fired warning shots into the air, the jury was told.
Part way through the trial Jasmine Hira Borrell, 26, of Welcome Bay, admitted two counts of assault in relation to two of the three adult complainants.
She was discharged on another two counts of assault with intent to injure and possession of an offensive weapon, due to insufficient evidence reasons.
Her brother Rihari Jarrod Borrell, 23, walked free from court on Wednesday after the serious assault charges he faced were dismissed, also because the Crown accepted there was insufficient evidence to continue to try him.
Jasmine Borrell, Ake and Drewry will be sentenced on October 14.