I know that my resort in the Mayan does not have witnesses for the symbolic ceremonies, but I plan to ask if they will do it for us.  For those people who may then know it wasn't a legal ceremony.

Unless you decide to put them as your wedding party I am not sure what you could do?  You could give them flowers, or you could make one an MC or make them both give toasts.  I would probably speak to my fiance about it once the sore spot of his brother not going has passed.  I don't think it's unreasonable to have them as your wedding party, it's not their fault his brother can't go (though it does suck).

I had a similiar problem. Needed one BM but have 2 sisters.  One wasn't planning to come so asked the other.  Then she is, felt bad, asked her too, she said no, so it all worked out. but was a stressful nightmare.

Good luck

I agree with calgarybride ask your fiance, you might surprised he might be happy having them in the wedding party. Try not to stress about it so much... it's your day! Enjoy it. 

I agree. I think we brides stress off things that the groom wouldn't even care about. If you cant have them in the wedding party then find something for them to do to make them feel included. Sort of a special project. This is what I am doing with my fiancé's siblings. I do not want to have a wedding party so I asked them to help coordinate, make invitations, that sort of thing