In the previous parts of the story, Draco attempted to cut Narcissa out of the wedding entirely. Unfortunately, the Malfoy vaults are funding the wedding, and Narcissa threatened to withdraw all her money, and possibly disinherit Draco. It's not exactly in the story, but Harry and Draco argue over it, specifically in part... 8, I think. So she does get a little say, regardless of how much these each loathe her.

Heh, I always saw the confrontation as being between Harry and Garrett, but who knows? Maybe Draco will get his day in the sun as well. ^_^ Thanks so much for reading!