A friend of mine texted me this weekend and said that her husband wasn't going to be able to take the time off for our wedding (they're traveling across the country), since he used most of his PTO for their honeymoon earlier this year. She asked if she could bring a mutual friend of ours as her guest instead. Despite my hesitation, I said yes because I didn't want to come across as having a conditional guest. However, the invitation was mailed to Mr. and Mrs. XXXXX, not XXXXX and Guest.
I'm not planning on going back on what I said to my friend, but I'm curious as to what the proper etiquette is in this situation. If your named guest can't come, is it OK to ask if someone else can attend?