AH spike comes back for xander and anya's weeding. Buffy is xander's little sister and a cheerleader

I remeber reading a fic where Buffy is Xander's little sister who had a crush on Spike before he moved away. He comes back for Xander and Anya's wedding and sees how much Buffy has changed from the nerd little girl she used to be. She is a cheerleader in college. There is also a scene where Anya wants Buffy to go wedding shopping and threatens to tell people how she dicovered the different uses for the shower head if she doesn't and Spike hears.

I know which one it is you mean, it used to be on the vampires-kiss, I have the title London Calling in my head, but if that's the title... I'm not sure.

oh wait, it's on this site, someone has asked for it already.
I can't post an url but if you search on find-a-fic just type in

buffy and xander sibbling - spuffy love and xander doesn't know it

and you'll find it! I was called London Calling