Her appeal has angered Armstrong's family who told Open Justice they feel like they have no voice in the process.
"David has no voice in the court," his mother Nicola Armstrong said. "I don't feel like I have any voice whatsoever."
She had believed Brunt would not appeal, and the news she is, was devastating.
"Why does she get the minimum when David lost his life?"
Brunt was sentenced in the Wellington District Court last month by Judge Michael Mika, who presided over the two-day judge-alone trial in which Brunt was found responsible for the fatal crash.
Lawyer Mike Antunovic applied for Brunt to receive a discharge without conviction, but this was denied at sentencing as Judge Mika deemed the gravity of the "extremely tragic" offending called for conviction.
Judge Mika said the cause of the crash on November 14, 2020, was that neither driver slowed to allow the other into the merged lane.
Brunt and Armstrong were travelling south along SH2 when the crash claimed the teen's life and injured Caron and Mark Lancaster, who were travelling in the oncoming lane.
Armstrong was behind a vehicle in the left lane and Brunt was at the front of the queue on the right, before they drove through lights and were supposed to merge 100m down the road.
Neither did, with both drivers travelling 400m at 103km/h side by side before disaster struck.
The left front of Brunt's vehicle collided with the rear side door of Armstrong's Nissan, causing his car to spin into the northbound lane and collide with the Lancasters' Toyota. He died at the scene.
Brunt had put other road users at risk by failing to yield and let the teen pass, Judge Mika said.
Armstrong was a twin to his brother, son, grandson and friend, and at Brunt's sentencing the court heard his death had significantly impacted his loved ones, as well as community groups he volunteered with.
