Rapana and Gray on Sunday are set to become the first brother-sister combination to both play on the NRL's biggest day.

Six years apart but close by nature, Gray will have the honour of being the first member of the family to run out on ANZ Stadium against St George Illawarra for a decider before Rapana follows suit.

Around 50 of the family will be there, after the huge cohort travelled from Canberra after Jordan's game on Friday to the SCG on Saturday to watch Tazmin play.

"There are 10 siblings, so eight of the siblings were there with their families and mum and dad as well," Gray told AAP.

"And there were extended families who made the trip as well. That just adds to the hype.

"My family are so supportive of anything we do. They are our biggest fans. For them it's a massive honour and they love coming to support us.

"We should get a bonus (ticket deal) because there are so many of us."

While Rapana is one of the most damaging wingers in the NRL and a Kiwi representative, Gray does her work in the middle and has played for Australia after being born in NSW.

She played in the Sydney Roosters' grand-final loss to Brisbane last year, before moving to the Broncos in 2019.

Rapana, meanwhile, could be gearing up for his last NRL game against the Roosters with the 30-year-old linked to Japanese rugby.

But despite their differences in allegiances and distance, the pair remain as close as ever and will speak regularly throughout the week.

"We talk a fair bit about footy," Gray said.

"It's obviously real good to have a brother like that. Growing up I always followed everything he did.

"He's a massive role model and playing in a grand final is the closest thing I will be able to do to run out on the field and play before him."

The two come from a talented rugby league family.

While 24-year-old Gray is the only of the four girls to play rugby league, all six of the Rapana males played as youngsters.

Jordan has been the most successful, but older brother Joel was also with the Titans last decade and played for the Queensland Reds in Super Rugby.

They once joked Gray could one day play alongside them in a decider, but Sunday is now far closer than they could have ever realistically imagined.

"We used to joke that I might be the first girl to be able to play alongside the boys," she said.

"But honestly, to be able to represent the Broncos and play before my brother is a massive honour."

Australian Associated Press