The Backstreet Boys star was expected to walk his younger sibling, Angel, down the aisle at her wedding to Corey Conrad at Newhall Mansion in Piru, California on Saturday (08.02.14), but opted to celebrate his own upcoming nuptials in Las Vegas instead.
The 'Everybody' hitmaker, 34, was noticeably absent from the ceremony, according to UsMagazine.com, but 26-year-old Angel's twin brother, Aaron Carter, was on hand to escort her on his own.
Meanwhile, Nick and his bride-to-be, Lauren Kitt, celebrated at a joint bachelor and bachelorette party at the Palms Hotel and Ghost Bar with approximately 15 friends.
The singer was clearly looking forward to the event as he shared a picture of their gift bags and champagne on Twitter on Friday (07.02.14), with the caption: "It's about to go down at @palms just entered the room of ecstasy."
Nick previously admitted his relationship with his family "has been toxic" at times and even claimed they blamed him for the death of his younger sister Leslie from an overdose in 2012.
The heartthrob skipped her funeral in favour of performing a scheduled concert and later told the 'Dr. Phil' show: "The communication is something that I'm still to this day trying to work on. ... It's tough when you come from a background like that and a home that is really up and down and roller-coaster."