Yeah, JKR said in an interview that she thinks that Alice's name was either Prewitt or Williams but she didn't know because she didn't have her notebook with her. That was an interview for GMTV.But it wasn't put directly into the books so you can have any name you want.
You could have a ball as a valentines ball, or maybe the head students could decide to have a Sweethearts Dance?
Love the story by the way!
I actually don't find it entirely unbelievable that Alice could have been related to Molly. It wouldn't have to be a close relation; perhaps they were second cousins? Since you have pretty much free reign here, you might as well invent a connection, if that's what you want, and since it's been mentioned by JK, at least you've got something backing it.
I think AurorKeefy's idea is the most plausible, regarding the ball. I like the idea of exchange students at Hogwarts.
I always thought that Karkaroff was a bit older than the Marauders, though. I mean, imagine being Headmaster at thirty-something! Even though he and Snape seem to be around the same age in the movies, you must remember that Snape and Lily and the Marauders are much younger in the books. According to the now official time-line they were born around 1960, and hence Snape was only 34 in GoF. I would have imagined Karkaroff to be at least a few years older.
Hope I've been of service!
For a ball, maybe not for the story in question, but just for the fun of writing about a ball, a teacher's wedding would be great, especially if the teacher in question had a small family and considered the students to be friends, and therefore wedding guests.
Flitwick, maybe? That'd be fun.
That would mean the ball could be held at Hogwarts during the summer, maybe right before school let out. Or maybe the older students could come back for it. Imagine all those people in formal robes tumbling out of the fireplace, shaking off their clothing, and muttering, "Wish I could just apparate."