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The 17-year-olds created history earlier this year when they won bronze medals at the Winter Olympics in PyeongChang in February.
Sadowski-Synnott became the first New Zealander to win a medal at the Games since Annelise Coberger won silver in France 1992.
A few hours later, Porteous also won bronze to take New Zealand's all-time total to three medals.
Sadowski-Synnott has been nominated for sportswoman of the year and will face some daunting competition from two-time supreme winner Lisa Carrington and queen of the court Joelle King.
Other strong contenders are are pole vaulter Eliza McCartney, Badminton horse trial winner Jonelle Price, rugby's Kendra Cocksedge and Michaela Blyde and and shot putter Sarah Goss
Otago and White Ferns cricketer Suzie Bates has also been nominated in the category.
Porteous is up for sportsman of the year but world champion shot putter Tom Walsh is a strong favourite.
He had a tremendous year, winning gold at the Commonwealth Games, retaining his world indoor title and also producing a massive all-time top-10 throw of 22.67m in March.
The hotly contested category also includes All Black Brodie Retallick, Commonwealth Games gold medal weightlifer David Liti, boxing Commonwealth Games gold medallist David Nyika and racing drivers Scott Dixon and Scott McLaughlin.
Otago athletes Adam Hall and Holly Robinson have been nominated in the para athlete/team of the year category alongside five-time winner Sophie Pascoe.
Otago's Raylene Bates has been put forward for coach of the year.
Ireland head coach Joe Schmidt has also been nominated for the gong.
His nomination comes just two weeks after the Kiwi-born coach was named World Rugby's coach of the year and his shock announcement to finish coaching after next year's World Cup.
Schmidt led Ireland to a 16-9 victory over the All Blacks in Dublin recently, and is widely tipped as the favourite to take over the All Black role if Steve Hansen was to step down.
Carrington's coach, Gordon Walker, Scotsman Clark Laidlaw, coach of the All Blacks Sevens, Black Ferns Sevens Allan Bunting and trainer of wonder Australian galloper Chris Waller are all strong contenders as well.
Otago para swimmer Hamish McLean has been nominated in the emerging talent category.
A record 93 nominations representing 43 sports have been received for the 56th Halberg Awards.
A shortlist of finalists will be announced in January with the awards ceremony in Auckland on February 21.
Nominees for the para athlete-team, sportsman, sportswoman and team categories will all be eligible for the supreme Halberg Award.
- additional reporting by The New Zealand Herald