Oh wow, how did I miss this thread? (collects Moxie Girlz)
From what I know about Moxie Girlz feet, the only way I've gotten feet was basically buying new dolls. I've never seen any feet come with fashion packs since I've basically bought most the ones that are out so far. XP The only set that I can think of that came with extra feet was the Summer Swim Magic dolls that came with a pair of shoes, a pair of flippers for their swimming gimmick and a pair of bare feet. I have never seen those dolls ever since last year. Kinda regret not getting them. >,>;
As for them being mixable with Bratz, I heard they're not switchable because one of them has bigger feet pegs than the other. Since they don't come in individual packs it might be hard to find them without buying new dolls for their outfit and feet.