I don't know :o)
The only thing I objected to in this whole thread was no pardon's decree that no single person should be invited to decide to bring a guest.... "So and so, and guest" is a very polite way to invite if you aren't sure. When they RSVP, they'll hopefully let you know if they are bringing a guest. But if cousin shows up with someone you didn't expect, and someone tried to throw them out, or tried to enforce some silly arrangement about where to sit, I'd be very ashamed. That isn't what's important.