"I'm excited! My baby sister [is] getting married [and] it's gonna be special to have the whole family there. We're gonna have a great time!" Derek shared with ET's Lauren Zima at the Los Angeles debut of Travis Wall and Shaping Sound's new show, After the Curtain, at Royce Hall at UCLA on Tuesday.
"It's gonna be like, a week-long event," he added. "It's gonna be amazing."