I am getting the way how to search those records, thanks.
I agree with you, by only finding Franz birth 1915 as well. Nothing for his death, or Karl's birth. And nothing for the other 2 siblings ...
I have decided to take a step back. The information I have comes from a book/diary written by Josef Karl (born 1919) when he was in his 20's, and which I have his baptism papers. How much of his details are actually accurate is now in question, but I will try every line I can think of to try and trace them.
Thank you all, for all your wonderful help.
Dave1948.