My G*D! That was outstanding! I definitely have to agree with all of the comments that the 4 of them had about the way things were run at Hogwarts under Dumbledore.
I was surprised at first that you used Parvati instead of PAdma considering your disclaimer at the top of your stories. Interesting explanation you used for the reason as to why she was there. I just figured that somewhere it had been mentioned that Parvati was the older twin. Is there a mention anywhere in cannon as to who it is?
I couldn't find any reference for which is the senior twin, and even the Lexicon is silent on the issue. So I guess its up to the writer to decide.