'P'-themed Birthday Party

I've been racking my brain trying to figure it out since I saw the film, but I still have yet to determine which character Emelia was supposed to be at the younger sister's birthday party...I understand that the film focused simply on the revealing nature of the costume, while neglecting to actually identify the character; however, I'm sure, well at least I hope, there's more to it than that. I thought that the theme was very clever, and I enjoyed the fact that the all of the family members were willing to play along. The other characters were clearly identifiable: the father dressed up as the Pope, the mother as Pocahontus, and the sister as Peter Pan, but who was Emelia supposed to be? Anyways, maybe I'm overanalyzing this, or reading too far into it, but I'm just very curious, and I feel like I'm missing something, so if anyone has any ideas, I'd really appreciate it if you shared them with me. :)
Thank you,
T.J.