"This is a team that's played together all year and they deserve the chance to play in the tournament."
The coach of the team Andy Lovatt told Stuff the 21 boys in the squad would either play in the tournament and forfeit any points, or would not play at all.
"It is important to question when situations seem to be unfair, and also important that students learn the processes by which to have their voices heard," Beaumont said.
"In this instance with the rugby game next week, we will support the voices of the rugby players and their parents in how they choose to participate."
Briar has played since she was five, in mixed teams, and more often than not as the only female. She also plays for the Tamatea club.
Her father Dean, the assistant coach of the team, told Stuff she was "quite upset" when he informed her she may miss her chance to play in the tournament.
"She asked me why, and I had to tell her someone thought girls shouldn't be in the team. It goes against everything me and her mum have told her in the past," he said.
In Hawke's Bay, girls can play in mixed teams until High School, or Grade 12 in the club system, at which point they play in female teams.
Mavis Mullins, who was the first woman appointed to the HBRFU board, said it was disappointing to see a young girl not being able to play rugby for her team.
"It does seem hypocritical that she can do this through the week and come to this tournament and they deem it not appropriate," Mullins said.
Although she didn't know much about the case she said it was a missed opportunity to make a statement of promoting diversity in sport.
"It could have been a real cause for the school to make around women and girls in sport," Mullins said.
"But this is a real opportunity to be proactive and make a change for the future."
A statement issued by the organisers to Stuff said by having girls and boys teams playing separately more students could play in the tournament.
It said there was equality if the sexes were separate, and there were health and safety issues as "boys can be bigger, stronger, heavier and faster".
"By allowing students of one sex to play in a team of another sex for these one-off tournaments sets a precedence [sic] that could see boys who play in a mixed netball/hockey team play for their school's girls' netball/hockey team [at the tournament] or vice versa. It could remove the need for separate sports, therefore meaning less students able to play," the statement said.
Green Party Sports and Recreation spokesperson Marama Davidson said Briar needed to be allowed to play.
"We need to leave these attitudes in the past, especially with kids. Briar is an accomplished player who has been playing club and representative rugby since she was 5 years old," she said.
"It's pretty clear that the organisers' attitudes weren't motivated by a concern for her safety.
"She has already played for her school and been awarded for outstanding performance.
"Rugby is a huge part of our sporting identity and girls shouldn't be excluded from being part of that," Davidson said.
