ISO of FIL's birth mother and family (born Nov. 3/53 in Montreal to Freida Zelman)

I am searching for my father-in-law's biological family. He was born to a Freida Zelman on November 3, 1953 in Montreal, Quebec. She was unmarried and 23 at the time. The father is not listed on the birth certificate, but information does state that he was a Israeli soldier from Jerusalem who was in Montreal for a short while. Freida was Jewish and we believe the father was as well. Freida was either born in Ottawa or Montreal, but she was a secretary in Ottawa for some time. My father-in-law's birth name was Barry. He was believed to be born at the Jewish General Hospital and adopted at a couple of days old to a loving Jewish family. Parents may have been somewhat tall, fair skinned but with brown hair and blue eyes.