The following excerpt on the B 534 fighter is taken from the book Foreign Planes in the Service of the Luftwaffe (1938-1945) by Jean-Louis Roba, here
https://books.google.ie/books?id=Ykc...G%2070&f=false
Avia B-534: This pleasant single-seater was admired and praised by the new owners. As it was captured in numbers (probably more than 300 B-534 fighters of all types – including Bk 534), they were largely used in the German Airforce, a training centre for this type of fighter having to be created at Herzogenaurach for the dispatching of the planes. But the Luftwaffe did not acquire all the fighters as some of them had to be given to the airforce of Germany’s new ally: the Independent Slovak State.
As the B-534 was a modern plane, they (i.e., the Germans) tried to include it in frontline units. In September 1939, a Staffel of II./Trägergruppe 186 received a few B-534s. A few of them were equipped with arrester-hooks and structurally strengthened for testing on the future aircraft carrier Graf Zeppelin. The experiment would last only a few of weeks, until the captured planes were replaced by Bf 109s, and pressed into school units. Another Staffel, 3./JG 70, was also temporarily equipped with these Avias.
The sole B-534 remaining in the frontline units were transferred into LLG1 and LLG2, the combat glider wings. The Czech machines were employed (alongside many other types, such as Ju 87s, Hs 126s, etc.) to tow DFS 230s. In 1940 a handful of planes were temporarily painted in Polish markings to play the role of PZL fighters in the Carl Ritter picture Kampfgeschwader Lützow.