Grace Wexler is not related to Sam Westing. Who is she related to?

Mrs. Wexler is related to Berthe Crow.

“Grace Wexler’s maiden name is not Windsor, it’s Windkloppel,” the judge exclaimed, riffling through the pages of Sandy’s notebook. “Here it is: ‘Berthe Erica Crow. Exhusband’s name: Windy Windkloppel.”