THEY say good things come in pairs but talented Northern Rivers' siblings Cecilia, Bridget and Monica Brandolini are proving three's not always a crowd.

The Byron Bay sisters, who perform in two separate outfits (Cecilia as a solo act and Bridget and Monica in folk duo Maple), will have a big say in the outcome of Friday night's Tweed Battle of the Bands final, after progressing through heats one and two respectively.

That both acts entered, let alone progressed to meet in the final came as a surprise for both Cecilia and Maple, with the opposing acts keeping tight-lipped on initial plans to enter the competition which began on June 2.

"I'm constantly entering me and Monica in things and we didn't realise we'd both entered until a week or so before, so that was pretty cool,” Bridget said.

"At first we thought should one of us step down, but we thought it was funny and thought we might as well see how it goes.

"It seems a bit weird that I'm going up against my sister, but because she's my elder sister, there's that competitive edge, so it's really exciting.”

Their respective progression to the finals would come as no surprise to fans, with the multi-instrumental siblings part of a highly talented family of musicians.

Cecilia, 19, reached the top 10 of The Voice Australia in 2014 as part of a duo with older brother Gabriel, while Bridget, 17, and Monica, 14, have been making a name for themselves as Maple over the last two years.

Representative of a singer-songwriter ideal which is synonymous with talented, well-known artists from the region, Bridget said Maple's sound is an eclectic blend of folk and pop in the vein of Lisa Mitchell or Angus and Julia Stone.

Inspired by family and female artists like Montaigne and Katie Noonan, the pair both play ukulele, while Bridget plays guitar and Monica the drums and keyboard.

"Mum and dad are both qualified music teachers and they're both really talented. They have a huge influence over our sound,” Bridget said.

The siblings form a third of the final's field, which also includes Gold Coast's all girl pop/rock band Chasing Velvet, and blues/rock outfit Stingin' Rogers from heat one, plus Cabarita rockers Catchpole and new wave Robina outfit Bligh from heat two.

Set to be played outdoors at Cudgen Leagues Club, the final will include a beer garden, food trucks and market stalls, while local act Mr Ed will close out the night.

Battle of the Bands organiser Kristie Hedley said a major point of difference for the family friendly, all-ages final was the emergence of female artists, who make up 50% of all finalists in 2017.

"Last year we only had one girl out of 12 bands, but this year's even split is great as girl power is back,” she said.

She said there was no early favourite for the title, with the overall standard a significant rise from 2016.

"In 2016 we had some stand outs, but this year every band was worthy of going through to the final, which made it hard to judge in the best possible way,” Hedley said.

Winner's will receive $2000 and direct entry onto the Buskers by the Creek Festival bill and Bluesfest's Busking Competition, which offers a significant opportunity for young artists trying to grow their base.

Bridget said the sisters would be happy regardless of the outcome, with the final making it the first time they'd ever competed against each other.

"We might go there and no one wins, but we get to hang out, so that's cool,” she said.

"I just want us to do the best that we can. If we win that'll be awesome, but if not, we're just happy to make the final.”

Tweed Battle of the Bands

Where: Cudgen Leagues Club

When: Friday from 5pm

Tickets: $10pp, $20 family, $5 child