Paul, your Dad must have been a real bada$$ to survive Stalingrad, and 8 years as a Soviet POW, and STILL live to be 99! Good thing for you, the apple doesn't fall too far from the tree...
As far as post WWII Germans in the French Foreign Legion, there is a fantastic book called: The Devil's Guard.
Amazon.com: Devil's guard: George Robert Elford: Books
There is some debate about how true the story is, but it's very believable and compelling. It's also basically a textbook on how to deal with guerilla's the SS way. Not a pretty scenario.
I owned this book many years ago and loaned it to someone who never returned it. I finally found it on Amazon.com and it goes for $200!!! Ouchy! So much for replacing my long lost copy.
In any case, here's another well deserved salute to your Father, Cyberia!
