The nine-member group had been asked to perform months ago and had been putting a lot of thought into the preparation of their 40-minute set, she said.
"They've got a line-up of bands in the Sunday night and we all have a similar approach to everything, a similar ethos and reasons why we write. We're excited to be supporting those bands and to be grouped with them."
Lines, 18, said she would be playing a half-hour set on Friday afternoon. Her set will be made up of some of her own songs, including her debut single Wannabe, and "a couple of covers".
"I'm really looking forward to it. I was feeling pretty nervous about the whole thing but the set is coming together."
She was also looking forward to seeing the other performances, particularly Gungor.
"I cannot wait to see them, they will be incredible live."
Lines will also be taking to the stage on Sunday night with Mosaic Music.
Festival One director Graham Burt said he could not wait for people to get to Mystery Creek to "sit back and enjoy this exquisite festival we have built".
Last year was the last time the well-known Parachute festival was run. It was cancelled as it was no longer financially viable.
Mr Burt said he went to every Parachute festival in its 24 years and was sad to see it go.
He said he and a group of friends were taking a walk at Waiheke Island when one brought up the idea of creating a new festival in Parachute's place.
"He said if he found a way, would I run it? That was it."
Mr Burt asked bands who had previously performed at Parachute if they would be keen to get on board a new event. The only ones who were not interested were those who were already booked out, he said.
The main difference between Festival One and Parachute would be down to the inspiration organisers had drawn from international music events such as Coachella.
"If you've ever had a friend who has been to Coachella, you ask them how it was and they'll go on for minutes without even talking about the bands. It's the whole experience.
"We won't get there in one minute but we're building that experience so people can come and do a lot more than just listen to music."