Buddykins could also work. I want to say Petunia called him Didikins in the books.My favorite nickname for the OG Buddy is Budley which is a portmanteau of Buddy and Dudley (from Harry Potter) because he acts just like him.
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So was it confirmed they were at the Grand Floridian last night? If the orange hippo didn't post today my guess would've been that they were doing a staycation there and were going to V&A's this weekend.
I also wonder if in addition to filling their gullets they went to Disney Springs to see if they could find something appropriate to wear since the Technicolor Patchwork Quilt of Death didn't work out. They have Anthropologie there and I know they do carry plus sizes (at least online) so maybe she could find something there. Not sure how the one in DS is but I know the ones I've went to can vary on what they carry in person depending on store space.