You know Rossini’s “The Barber of Seville” and Mozart’s “The Marriage of Figaro.” But few know the final piece in the Beaumarchais Trilogy, “The Guilty Mother.” Well, now New Yorkers will get a chance to experience Darius Milhaud’s adaptation known as “La mère coupable,” which will be performed this summer at The Garage on W. 50th Street. Performances will take {…}