It's been my experience that the wedding is primarily driven by the bride (I know mine was). How would you felt if your SO told you that he/she wanted their siblings in the wedding party? Well, I can tell you: I wasn't happy about it when my H asked me if his sister could be a bride's maid.

In an ideal world, the bride's maids/groom's men are the best friends/one's that are the closest. Apparently, the bride does not feel close to any of you. I, personally, would try to let this go. In the grand scheme of things being in the wedding party is but a very, very small blip on the roadmap of life.

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Mental that one, I'm telling you. ---Ron Weasley, "Harry Potter and the Chamber of Secrets"