While Sheppard's six members have no doubt worked hard in recent years to establish themselves in the music industry, they would no doubt be giving equal credit for their American TV debut to their support network.

"There are so many people who help us do what we do," said Amy Sheppard, the band's aquamarine-haired keyboardist and vocalist.

"There's no way we could do it alone."

For Amy and her siblings George and Emma, it all started with their parents Greg and Linda, who watched as their children began writing songs and singing harmonies together, and from 2009 encouraged them to make it their focus.

"Our Mum actually tours with us and acts as our tour manager a lot of the time," Amy said.

"They were really our first believers, our first supporters, and they've made [our career] their dream as well."

With Jason Bovino, Dean Gordon and Michael Butler rounding out the band, the Sheppard parents founded a record label, Empire of Song, and bankrolled their first EP in 2012, which contained their first Australian hit Let Me Down Easy.

Greg Sheppard worked as their talent manager, with Linda the main tour manager until recently, and still travelling to manage luggage, equipment, transport - and provide a comforting hug after a hard day on the road.

"It's the little things - someone will ask for an autograph and Mum will say 'Here's a pen'," she said.

"As well as a mother and a tour manager, she almost works as our personal assistant - you really need someone you can trust who knows you."

Far from taking advantage of their parents though, Amy admitted the senior Sheppards kept egos and schedules in check.

"If we feel like having a party, Mum's like 'Come on, we've got a 5am flight, it's not happening'," she said.

"She keeps us in line, that's for sure."

Stewardship of Sheppard's international career became legendary promoter/manager Michael Chugg's passion after he heard the siblings do an acoustic set.

"We put a team together around them - an agent, radio delivery, distribution network and publicity," he said.

"There's a lot of Brisbane connections, as we manage a number of other Brisbane acts including The Griswolds and Megan Washington."

Months of hard work saw Geronimo hit number one on the ARIA charts for three weeks, knocking off Pharrell Williams' monster hit Happy.

An international record deal with Decca followed, with Geronimo taking off in the UK and the band supporting Keith Urban on his Light the Fuse tour mid-year.

Having seen many superstars in his 67 years, Chugg remains excited about his young charges.

"I fell in love with the songs the first day they nervously played them in the office," he said.

"To watch them mature, to be around as Geronimo was written, watching the growth of the band onstage…they really are an exciting live band."

After wowing Ellen, Sheppard will continue a US promo tour, plus a number of European dates, before returning home for the ARIAs on November 26.

Singer and drummer George said seeing the band nominated for seven gongs was a special moment.

"We've all been on this crazy rollercoaster together so it's a win for the whole Sheppard team," he said.

"We're all extremely excited."