Nick Jonas has promised his brother Joe Jonas' bachelor party will be "very respectful"

He told E! News: "It's our bachelor party. As much as it's for him, it's really for all of us.

"We got no plans yet. It is going to be very respectful, very respectful. We're going to have fun. We have to! He's gonna get married. It's a big deal."

The 25-year-old star previously admitted he was "thrilled" the 'Game of Thrones' actress will be joining his family.

Speaking after Joe, 28, and Sophie, 22, announced their engagement last year, he said: "I'm thrilled. She's an amazing person and I couldn't have asked for my brother to find a better partner. I'm so thrilled for him and for her, and she's a beautiful new addition to our family."

Meanwhile, Nick and Joe's dad, Kevin Sr., previously admitted he already thinks of Sophie as a part of his family.

He said recently: "[We] love the way that Joe loves her and the way that she loves him. We're a blessed family to have her as our future daughter-in-law - and, in our minds, [she's] already a daughter-in-law!"

Kevin is also a huge admirer of Danielle Jonas, the wife of his eldest son Kevin Jr, who have daughters Alena, four, and Valentina, 18 months, together.

And he feels similarly enthusiastically about Joe's impending marriage to Sophie.

He shared: "Danielle is a wonderful daughter-in-law. She's given me two wonderful grand-babies, and we love them. And Sophie comes in: From the first time we met her, we knew she was a special young lady."