Wedding question

[csbdr]

Just wanted a quick opinion. I just went from being a guest at my brother-in-laws wedidng to being IN it as a usher. I had been plannning to wear a tweed jacket and vest with my kilt, but now feel like something a bit sharper may be called for. This is not a kilted weding, but he wants me to wear the kilt as an usher. He is getting married in October, on a Sunday morning. It is also not a very formal or even organised affair. I think he is having his ushers wear what they wish, so likely suits. I asked him how the others would be sdressed, and he said no tuxedos, but then was vague regarding anything else, saying there is "no real expected dress...) whatever that means.

Anyway, I was considering getting a black jacket to wear instead of the tweed, and was wondering if that would be the best choice? Obviously nothing more formal than that is warrented.