Doting younger brother Rob told ET Canada that words couldn't express how excited he is by Lizzy's success so far on the ITV talent show.
Lizzy received four yeses during her first audition for the judges to progress to the next round of performances.
"It's amazing!" he said. "Her being on that is the most exciting thing to happen to me in such a long time. I'm SO excited about it. She's really good!"
The Twilight heartthrob also said that although he's written songs and performed in the past, he's never sung alongside Lizzy.
"We have really different taste in music so we always get into arguments," he revealed. Friendly arguments we presume!
Lizzy's audition was aired on last weekend's final episode of room auditions. The judges were unaware of her famous brother although Simon Cowell did keep asking if he'd met Lizzy before… family resemblance, perhaps?!
It meant Lizzy proceeded to the next round base don her own merits with all four judges saying big fat yes!
A source had said previously: "She didn't mention she was related to him to any judges or producers. It's important to her she does not fall into the trap of just becoming Rob's sister."
The former receptionist who now works as a personal assistant will audition next in the arenas in front of crowd of thousands.
Rob previously was quoted saying: "I'm so ridiculously proud of her. I would never have the balls to do it in a million years. I can't believe she's done it. It's amazing."
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