Since Father migrated thru Germany, contact the Bad Arolsen Archives. Germans kept meticulous records. These archives will provide you w/details of his exact experience in Germany and other personal details. Inquiry by immediate family is available for free. All you need to provide is his full name and any other spelling variants and his exact birth date, or as exact as you have it. (If Mama was a DP, WW2 Displaced Person, you can make an inquiry for her at the same time.)
Do not provide more info than that.You want archivists to look everywhere in their 5 miles of DP documents. Your inquiry can be done by e-mail. I understand the archives have upgraded their service and response can be received via e-mail as well. Response can take as little as three days or as much as three months.