I believe that the Johann Friedrich Radtke you talk about is the brother from my great-grandfather Wilhelm Christoph Radtke. Johann is born 1. june 1850 in Drzewianowo / Hohenwalde Kr. Wirsitz. and christened 23. june 1850 in Mrotschen. His father was Johann Radtke, mother Rosa Radtke nee Wrahse. If you think that cold be possible please reply to me.