Kevin Jonas' five-year-old daughter almost ruined the news of the Jonas Brothers' rumoured reunion, by telling her whole school about it before the comeback had been officially confirmed.

The sibling trio returned to the music scene earlier this year with the release of their comeback tune Sucker, and are about to start their Happiness Begins Tour. While the brothers discussed a potential reunion for a year before it actually happened, Kevin's daughter Alena failed to hide her excitement about her dad and uncles hitting the stage again - and decided to tell all her classmates.

"She did tell her entire school that the Jonas Brothers were coming back - before the Jonas Brothers were (officially coming back)," Kevin laughed as he was interviewed with brothers Joe and Nick on The Tonight Show Starring Jimmy Fallon on Wednesday night.

"We were trying to keep it a secret for basically a year," Nick added. "We were making this documentary (Chasing Happiness), making the album. And we're like, 'We got this on lock. No one's gonna tell.' Kevin comes home and says, 'Guys, Alena told her whole class'... Luckily, those five-year-olds (were) tight-lipped."

"They kept the secret for us," Kevin smiled.

Kevin shares two daughters with wife Danielle - Alena and two-year-old Valentina. He's the first of his siblings to become a father, although his brothers have both recently become married men - Nick to Priyanka Chopra and Joe to Sophie Turner.

Joe tied the knot with Sophie Las Vegas at the start of May, but they are set for a bigger ceremony in France later this month.