Jill Ubdegrove, event manager for Massive Events, tells the story of how a last minute celebrity addition can shake up a show. It was Monday afternoon, and Sherlocked, the Sherlock convention, opened on the Friday evening.   The schedule was published and the visitors were excitedly planning their weekend. We had announced more than 10 guests, photo shoots, talk schedules were confirmed and actual sets and costumes had been acquired. Ten m...