While the 28-year-old triple-threat star is planning a wedding, her older brother, Derek Hough, is gearing up to star in Hairspray: Live
. Luckily, he can turn to his sister for advice, as Julianne played Sandra Dee in the Emmy-winning Grease: Live
. "I was like, 'Just have fun and enjoy it and get to know the cast,'" she shared. "He's just embracing it and enjoying it. It's a once in a lifetime kind of thing, so I'm happy for him."