Mel & Lia as their Alter Egos Mr & Mrs Rookwood to start
Lia had actually full on stalked a pureblooded couple she knew had been invited to the wedding, but were more than likely not to attend due to various ailments. She couldn't exactly remember how she came across the information, but all it took was her "twisting" her ankle in front of the elderly couple and leaning on the two of them several days prior to score the batch of human genetic code she needed to pass along to Mel for her polyjuice potion.
And after their bout of early day drinking, the two donned their respective outfits while also stashing party clothes for later, and drank down the disgusting tasting potion. "God, this is worse than fucking anything," she complained, but within moments they were old and wrinkled and completely disguised as their alter egos Mr. and Mrs. Jeremiah Rookwood.
Looking over her best friend, she gave her a wink. "I'd still totally do you," she joked in her man body, before they walked outside and apparated directly to the front gates of Cornfoot Manor. Getting in was a breeze, and Lia was actually sort of astounded by it. "Alright, should we find our seats, or the bar? For the record, I totally stashed a flask in this fancy coat if we have to wait too long.."