answer: There will be 13 people at the dinner party but #Person2# thinks 13 means bad luck. #Person1# doesn't think the number is a problem but #Person1# will invite #Person1#'s sister to make it fourteen.
documents: #Person1#: Ok, so who are we going to invite to our dinner party?
  #Person2#: Well, we have the Thompsons, the Greens, and the Anderson, about twelve people total.
  #Person1#: Don't forget my friend Andy from the office. He has nothing to do on Friday, so I invited him over.
  #Person2#: But that makes thirteen people! We can't have thirteen people for dinner on Friday!
  #Person1#: Why can't we?
  #Person2#: It's an old superstition. If we have thirteen people at the table, then it means bad luck. Can Andy bring a date?
  #Person1#: I'm not sure. He just broke up with his girlfriend recently, and I don't think he's in the mood to start again so soon.
  #Person2#: But we can't have thirteen for dinner!
  #Person1#: I think you're making a mountain out of a molehill. It's only a superstition. It really doesn't mean anything.
  #Person2#: Absolutely not! I refuse to have thirteen people for dinner on Friday!
  #Person1#: Ok, ok. I'll ask my sister to come. That way we'll have fourteen for dinner.
  #Person2#: That's better.