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Dear Prudence,

A recent inquiry regarding replacing the designated maid of honor has prompted me to seek your assistance. I asked my younger sister, age 20, to be my MOH. But she is making the planning of my wedding a nightmare. I had thought it would be a kind gesture if I asked her to pick out the dresses for the bridesmaids. We visited three bridal salons, and she made a veritable scene in each one. She was unspeakably ugly to both my mother and me, as well as the staff (swearing, sarcasm, and just plain rudeness). I was deeply embarrassed, and she apparently doesn't understand that this is not going to be "her day."

I asked her to help address envelopes and other little things that need doing, and she refused: "Not in the mood." The icing on the cake is that when she asked if the MOH is supposed to make a toast at the reception and I said it was traditional, she flat-out refused. Both my mother and I have tried speaking with her, but that just unleashed foul behavior. I am sick of her antics and fed up with her. I realize that asking her to relinquish the "title" may jeopardize our relationship, but I don't understand her behavior at all.

--T.H.

Dear T.,

Prudie does. The little sister is competitive with you, and there's a chance she wishes the bride and bridesmaid roles were reversed. Acting out in stores and "foul behavior" are indicative of emotional problems, deep hostility, and no self-control. By all means withdraw the "title," and tell her you do not wish to burden her with MOH chores, nor do you wish to have your dream day spoiled. There is not a reason in the world that you should have to tolerate this pill of a sister. In fact, suggest that she not attend the wedding. You need not be the victim of her neuroses.

As for "jeopardizing the relationship," with all due respect, it sounds as if it's already on life support. Just because she is your sister doesn't mean she gets to behave less well than a friend. Sometimes a relative is just an annoying person courtesy of DNA (or, if you're religious, a punishment from God).

--Prudie, proactively

Dear Prudie,