I don't see that you'd be breaking any etiquette rules, and the idea seems sweet. But, you would be giving up the role of mother of the bride and possible planning parties that the mob wouldn't typically be hosting.
I suppose if you and your daughter love the idea, and the two of you are as close as best friends or sisters, then there shouldn't be a problem. Top Wedding Questions Forum Moderator - "Write your sorrows in the sand, your blessings in stone".