I am just curious about this although my wedding is still several months out (I saw a similar post on another wedding website but I feel that they have questionable advice) but I was wondering if there is any specific protocol for guests who RSVP yes and don't show. I understand that things come up (health, personal issues, etc.) that are out of anyone's control but what is the best steps for the guest and host to take if there is no reason given and they just back out? What if the guest never mentions anything before or after the no show? I know that gifts are never required but if you had to cancel last minute for a wedding would try to cover your plate?
My main reason for curiosity is that I have heard from several of my FI's family members that a certain member of the family always RSVPs yes and never shows to any event. If said family member RSVPs yes, I will definitely include that person in seating charts, etc. but I know that I would be very disappointed and very unhappy that I paid a large amount of money for their meal and evening and they didn't even give the decency of a phone call.
Just curious...