I would get to the reception site early and switch cards!
Other than that, if the Bride or groom is a close enough friend you could ask nicely if they could move you to another table so you can meet others from your congregation. If it's anything like our church, someone made out the seating chart years ago, and nobody has seen to change it. Good luck. It's kind of a sticky situation.
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Sharon
If you are coming to see me, come any time! If you are coming to see my house, make an appointment.