Read something once (which I haven't verified the accuracy of) that talked about how the king of Russia, England
, and Germany
were all cousins at the time of WWI.
Kaiser Wilhelm apparently once said, "If my grandmother had been alive, she would never have allowed it."
So depending upon how silly you'd like the dinner theater to be, you might have a surprise (beyond the grave) visit by a very upset Queen Victoria! A seance theme, perhaps!