Who Shall Go To The Ball?

In canon, Harry Potter instantly rejected all the girls who asked him out to the Yule Ball, saying 'no' without a moment's consideration. Here though, he says 'yes' to them all without thinking instead, and finds himself spoiled for choice, facing a bit of a dilemma. Who are all of these girls anyway? And which one should he pick to be his partner for the Yule Ball?