Outside professional singers sang the roles of Maria, Captain Georg Ritter von Trapp, the Mother Abbess, Liesl (eldest child of Captain von Trapp), and Rolfe (the postman). Members of the chorus sang the roles of Baroness Elsa Schraeder, Max Detweiler, the four other nuns (Sisters Berta, Margareta, Sofia, and Teresa), and three of the von Trapp children (Louisa, Brigitta, and Marta). Children from the wider Vienna community sang the roles of the remaining von Trapp children (Friedrich, Kurt, and Gretl).