Instructions for Finding William Morningstar

Who found out that the waitress knew William?

The correct answer is Sancho.

In the play, Sancho and Bolsa are sent to a restaurant called "The Purple Cow" by the cemetery groundskeeper. When they get to the restaurant, they are given a table and menus to look at, and told their waitress will be there soon.

As they are waiting, Sancho and Bolsa talk amongst themselves and decide who will ask questions about William Morningstar. The waitress named Robin came to get their order, and it was Sancho who asked if she knew William. She proceeded to tell the men how she knew William and where he may be hiding out.