looking for mothers birth father

Please help if you can. My mothers story is not unique. Her birthmother met Daniel Du Marc during WWII, and they had an affair. She had just got married, and upon falling pregnant, her husband told her he would not raise another mans child, and ordered her to give the baby up for adoption. Edna (my mothers birthmother) wrote to Daniel who was in the Canadian Airforce (we believe), but the letters kept missing him. Finally, he received word that Edna was pregnant, but this was almost 8 months into the pregnancy. He immediately applied for leave and returned to England. Going to Ednas home, (she had moved to the country for the birth and adoption) he enquired with her sister as to where she was. Her sister told Daniel they had both died in childbirth. Obviously, as I am writing this mail today, she diddnt die. Mum found her birthmother some years ago, but she had thrown away all documents pertaining to Daniel. All we have to go on is the his name was Daniel Du Marc (we've tried all the spelling options) and he was in the Canadian Airforce. His family had a chain of tailoring shops in Montreal. His sister was called Deanna. That is all the information I have. Please, please help with any information. I have been trying for so long, but I cannot give up hope. The reason my mother wants to find her birthfather, or half siblings is to find 'someone she looks like'. I apprecaite any help! thank you Samantha Guillaume