Is it necessary to ask an older family member (in this case, a first cousin) to be in my bridal party because I was in her wedding five years ago? If I ask her, I will also feel obligated to ask her two sisters.
It is not required that you ask anyone to be in your wedding party. You should choose the people you feel closest to. That said, not everyone feels this way, and your cousin may be hurt by your decision. So be prepared to talk to her about it. Simply explain that there were a lot of people you wanted to include, it was really hard to decide, and so you chose only your closest friends and siblings. Because she was married five years ago, chances are she has been in a few weddings and will be perfectly happy attending as a guest.
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Your Bridal Party