The This Is Us star has always been impressed with the British actress' looks and she would love to spend time with her talking fashion.
"If I were friends with Sienna Miller, I'd like to raid her closet," she tells Us Weekly magazine at the New York Fashion Week presentation of Alice + Olivia's new collection. "We're not friends, but Sienna, I'm absolutely open!"
Mandy has been receiving rave reviews for her own style on the red carpet this awards season in clothes and accessories loaned to her by some of her favourite brands. The feedback is bittersweet for the former child star, because she always has to return the items - and she fears she'll never be able to repeat the look in other clothes.
"I was pretty sad to send the Naeem Khan dress I wore to the Golden Globes back," she admits, "I was like, 'Aww, that's my superhero cape'.
"(Shoes and jewellery are the worst to hand back) because you're like, 'I could actually re-purpose that. I could wear that again. I could find a totally inventive new way to rock that'. So that's always a bummer."
However, when loaned outfits make their return to the original owner, Mandy mourns the clothing by buying new stuff on the internet.
"I'm going to be honest, I'm a Shopbop and Net-A-Porter addict," she shares. "Yeah, it's bad. You know what I love? The ease and convenience of shopping online. In fact, it's too easy I think, but it's too much fun!"Read more at:cocktail dress australia