Unless you are a part of the couple, the wedding is NOT about you. If you care about the couple at all, you will make any judgment calls based on what is best for them. If two people can be in the same place peacefully, but someone bringing a specific guest makes it a circus, DON’T take the guest.
Nicholas, your friend may be nice, but she isn’t the one who was invited. This isn’t about you and it isn’t about your friend. If you want to introduce your friend to people, then plan something and invite the people over. Don’t use someone else’s wedding to make a point. I repeat, weddings are about the couple getting married. If you can’t put the couple’s best wishes in front of your own for that ONE day, I hope you enjoy the buffet.
Put yourself in the couple’s place and think how you would feel if someone decided to hijack your special day.