I could use some advice on the topic of uninvited guests to a party. I've read up on it a bit and understand that the general etiquette is as a guest, you shouldn't bring along people who weren't invited, and as a host, you should graciously accept those uninvited guests when they show up.
What do you do when this is a repeat problem? I'm laid back about BBQs and birthday bashes, but when I have a dinner party or small ladies' night, I'd like to have some choice on the tone for the evening - and having enough chairs for everyone! Is there anything that can be said in the invitation to drop the hint this is not welcome? These are not formal events and it is customary in my circle to invite electronically, so paper invitations/RSVPs would be odd. It wouldn't work anyway, because I'd get a text message two hours before the party announcing that so-and-so will also be joining us.
Excluding the offenders is not an option.