You would invite people you don't know to a party? Have just had an invite to a double birthday party from 2 people who I haven't a clue who they are. I suspect that it's dp's cousin and Ds. I've been with dp 21 years, through funerals, weddings, other parties etc, and I have never let these folk. Dp had a vague notion that one is his cousin, but doesn't know the youngest.
Why on earth would you invite people you don't know to a party???