Willy Köstler

Not much is known about Willy Köstler. It seems he was active as early as 1867, but it is unclear when the company ended production. There was a "Willi Köstler" still living in Graslitz in 1930. There are reports that a "Willi Köstler" was killed in 1938, but there was also a "Willi Köstler" with connection to the musical instrument industry still alive in 1951. What the relations between these Willy and Willi's are, and when the "Willy Köstler" workshop was active, is a mystery to me.