I've just seen your 2013 posting about your father. I've also reveived my father's war records from the MOD and was surprised to see that he served in the German army. Like your father he was captured by the allies and immediately switched to Polish forces under British command, fighting at River Senio and the Battle of Bologna/Lombardy Plain.
The MOD also sent me his medals and his German solbuch, as well as numerous documents written in Polish. He died when I was quite young and my late mother believed that he fought at Monte Casino; if that were true he must have been on the German side at the time, judging by the dates supplied.
I followed his trail on demobilisation to a farm in the Scottish borders but, although a daughter of the farm owner remembered Polish soldiers there as a child, she didn't recall any names.
The soldbuch contains several loose photos, presumably of colleagues in the German army. As they both fought in the same place at the same time, might there be a small chance that they may have known each other?
In any case, I'd be very interested to hear if you found answers to any of your questions.