Staying up past bedtime - FTM

I have a dilemma and am not sure what I should do! I have a family member’s wedding this weekend and they want our 7 m.o. to attend with us. The issue is, they are doing a reception only, and the reception starts 6pm, and baby normally goes to bed between 6:15-6:45. Do you think I should I keep her up past her bedtime for a few hours to attend the reception? Or, should I keep baby home and have a relative watch them to keep them on their schedule? I just know baby will be grumpy if I keep her up too late and potentially not sleep well. But I also know that weddings are typically a once in a lifetime ordeal, so I don’t want to offend the bride and groom if she doesn’t come. Help!!