The Twilight star's older sibling Lizzy has sailed through the arena auditions for the upcoming 11th series of the TV talent show and is set to face the judges at boot camp this weekend.The actor said he is overjoyed she has made it through to the next stages, adding he wouldn't have the guts to do it himself, reported The Sun."I'm like so ridiculously proud of her. I can't believe she's done it. It's amazing," he said.The 28-year-old added: "I would never (be able) to do it in a million years."Show insiders said that the judges - Simon Cowell, Cheryl Fernandez-Versini, Mel B and Louis Walsh - were won over by Lizzy's soulful voice, and that she initially kept quiet about her celebrity connection."It was really important Lizzy was judged for her voice on the show and not as Rob's sister - that's why she hid the link at first," the source said."But she couldn't keep it under wraps for long. During her audition she was asked about him but all she said was he was very supportive. She's not the kind of person to cash in on the connection. However far she goes, she wants it to be on merit."The new series of The X Factor, with Simon and Cheryl returning to the UK panel for the first time since 2010, will air on UTV from 30 August.