Many converts have questions about dealings with their non-Muslim family after their conversion, but this one is, I think, far more rare. My brother's fiancee just asked me if I would be a bridesmaid in her wedding. She and I have been close for a while--she's known me since before I took Islam and has always been very supportive of it.
And she clearly spent some time thinking about the issue as well, including the fact that I cover. She's having her bridesmaids wear color-coordinated dresses, though with different styles. When I brought up the issue of my scarf, she suggested I could wear a long dress with a jacket and a coordinating scarf--see? she'd thought it out. The only excuse I was really left with at that point was that I wouldn't want for me to be the focus of her wedding--she should be the one in the spotlight, and I was afraid that in a scarf I might just attract to much attention. But I think she really did want me to be a bridesmaid.
I don't know of any Islamic objections--it's not a very religious ceremony, not even in a church, and if I could certainly be properly covered, I don't know that there's any reason on that front for me not to do it.
She asked me to think about it for a few days and then tell her later. InshaAllaah I'll pray istikhara on it, but just wanted to air the question to see if any of my readers might have some advice to contribute. Jazakumallahu khayran.