How many movies have Alexander Grill and Franz Josef Gottlieb collaborated on?

They have worked on 9 movies together! Their first movie together was When the Mad Aunts Arrive (1970) while their highest rated movie together was Tante Trude aus Buxtehude (1971). They have not worked together since Tender But Cheeky Like Oskar (1980). They are most known for their comedy films together.