Hi Katharina,
I think it would be good to open up a board called "Radetzky/Radecki/Radetz".
In my family, there up to today those, who spell the name "Radetzky", others who spell it "Radecki", like the writer Sigismund von Radecki and some others, living now in Germany and Canada.
Every Radetzky/Radecki who has a Website, can send me a message, because I would like to fill up the "Radetzky-Portal" which you will find (pardon: only in German language) under
www.radetzky.de or
www.vonradetzky.com.
Ciao
gerda v. radetzky, Munich, Germany