Unfortunately I have found myself in a pretty sticky etiquette situation I hope all of you can help me out with. I will do my best to keep this short while still including all relevant information:
We sent RSVPs out to our guests back in February. A couple of days after sending them out my parents asked me to include one of their cousins and aunts on the guest list. I replied that I would invite them but didn't send a STD. A couple of months later we had a meeting with the venue and found out the space was more limiting than we had first realized and that our guest list now exceeded the space by about 35 people. This was an unpleasant surprise but since our guest list was almost entirely people traveling we figured we would risk it. I realize this wasn't the most etiquette friendly way to proceed but we didn't really have much of a choice since we had sent out Save the Dates to everyone and were in pretty deep with this venue.
Anyway we sent out our invitations about a month ago and hoped for the best. A couple of days ago my mom asks me about the invitation for her cousin/aunt because they haven't received it. I told her I was so sorry, I had completely forgotten about them and unfortunately we just don't have the room to invite them.
What should I do now?
a) Call the cousin and explain that there was a misunderstanding with the guest list. "I am sorry you were told you would be getting an invitation but unfortunately we have less space than we thought we would."
b) Invite the relatives and hope for the best. Altogether this would include probably 6 more people who would definitely be coming. We have received some declines but not enough that we are in the clear yet.
c) Wait until we get enough declines that we can fit all of these people and send them invites.
d) Send them invites now but call and tell them we don't have enough space right now and we will let them know if there is an opening.
e) Your suggestion