Should i do this at my wedding?

I get on well with my SIL and still didn't ask her. I'm not sure why, but I don't think she was interested in doing it, and we only had a small wedding so I didn't want a lot of bridesmaids. She sounds like an idiot anyway, so you're better off not bothering. She sounds a bit like my sister, who wore a pair of Doc Martin boots to my wedding. I didn't ask her to be bridesmaid either as I knew we'd have problems agreeing on a dress etc...