The band — consisting of brothers Joe, Nick and Kevin Jonas — kicked off their 20th anniversary tour on Sunday at MetLife Stadium in their home state of New Jersey. But to make it more special, they surprised their fans with some special guests throughout the show, including Demi Lovato .

Reflecting on her recent surprise appearance at a Jonas Brothers' concert, the 32-year-old singer called the performance both 'special' and 'healing.'

The Jonas Brothers welcomed Joe Jonas’ ex-girlfriend, Demi Lovato, onstage for a surprise performance at their first concert on their Jonas20: Greetings from Your Hometown tour at New Jersey’s MetLife Stadium on Sunday night.

Lovato and the Jonas brothers performed renditions of “This is Me” and “Wouldn’t Change a Thing”, both of which featured in the 2008 Disney Channel film Camp Rock, which saw Joe and Lovato – who had a real-life, albeit short-lived, romance in 2010 – play love interests on screen.

During their commentary on food, Joe Jonas revealed a surprising childhood snack that the brothers specifically requested to have on hand for their 20th anniversary tour, which ki

The pair sang "This Is Me" and "Wouldn't Change a Thing," 17 years after the Disney Channel original movie was released.

Greetings From Your Hometown,” began August 10 with a special anniversary performance featuring Demi Lovato. The trek, formerly scheduled to visit Comerica Park later this month, will now play Little Caesars Arena.

Watch Jonas Brothers and Demi Lovato perform 'Gotta Find You,' 'Wouldn't Change a Thing,' and 'This Is Me' at Metlife Stadium tour opener.

The Jonas Brothers’ 20th anniversary tour marks a significant milestone for the group, coinciding with the release of their new album, Greetings From Your Hometown, on August 8. Lovato joined their show to honor their shared past and to focus on new plans ahead. Just a week before, she dropped her single “Fast” as part of her upcoming music album.

Joe, Kevin and Nick of the Jonas Brothers and Lovato starred in the 2008 Disney Channel Original Movie, Camp Rock, and it’s 2010 sequel Camp Rock 2: The Final Jam, where Joe and Lovato play love interests onscreen. The pair also dated in real life in 2010.

On an appearance on The Ellen Show, the host inquired about the song’s subject. “There’s supposedly a song about Nick Jonas,” Ellen stated to Demi, to which the singer said, “Ya know, something that I will always keep to myself is who I write my songs about.”