Halfway through and I thought my guests really got the whol RSVP thing. Now I need help! A woman I used to work with is invited to the wedding. She has been seperate from her husband for like 15 years, they only do not divorce because he has amazing insurance (as a truck driver). I invited her on her own. I received her RSVP today and she added her adult daughter to the RSVP. I have never met her daughter and I am not comfortable because we cut down our guest list to accomodate our small wedding, and, in the process, cutting people I would have liked at the wedding.Now, I don't really want to accomodate one of her kids randomly.
First, am I in the right here? Second, help me figure out how to tell her no

D,
I received your rsvp today and we are very excited that you are going to be celebrating with us. I am really sorry but we did not plan on adding plus ones.
I have nothing else

Please help me!!!