Just wondered how on Earth I can do this?
He was from Hong Kong, a drug addict and according to my birth mother (whom i’ve met a couple of times), all she knows is that he is pretty untraceable as he wevt back to HK and for all we know, he could have died of an overdose.
Not sure how I would really get in touch with him to be honest, as his Chinese surname was the equivalent of Smith, so it would be like looking for a needle in a haystack. I also doubt the local authority who placed me for adoption would have a clue as they lost my file, and took ages to find it when they were in the process of tracing me for meeting my birth mum... 
Anyone had any success with anything like this at all? How did you go about it? And where do I even start?
Any thoughts etc would be really appreciated. 