What's the rule about guest substitutes? For example, Jack and Jill are married and invited as a couple to the wedding. Jill has a friendship with one of the moms, but not the bride or groom. Jack can't come, and Jill refuses to travel alone, so Jill says she's bringing their daughter instead of Jack, or she's not coming. The invitation was addressed to Mr. and Mrs. Jack, not Ms. Jill and guest.
Thoughts???
Thanks!