Dear Prudence,
My wife and I have recently learned that we are going to have our first child. The pregnancy was unexpected. Nonetheless, this is wonderful news, except for one thing: The due date falls on the same day as my sister's wedding, which will be held eight hours from where we live. My sister loves being the center of attention, and we worry that she will think we are trying to steal the spotlight on her special day. We are almost certain that she will throw a fit when we tell her that we cannot attend her wedding, because she has a history of throwing temper tantrums over perceived slights. We feel terrible about the situation, but there's nothing we can do about it. Any tips on how to break the news so I'm not writing to you again in a year about my estrangement from my sister?
—Unexpectedly Expecting