As you have already heard it is the Bride and Grooms day and you want to do nothing to take away from that.

If you have jacket accessories to dress your kilt up with the proper formality for the wedding then by all means show your mother the many pics on the forums and hopefully she will change her mind. If you don't have the right outfit then skip the kilt. A situation like this is not the place for a rebel look, a utilikilt or other kilt-like garment.

So often we tell guys here to be themselves and be proud of what they wear. Along with court this may be one of the times to go with societal norms rather than your tastes.