In search of Macklin Brown b. c1920

Day before yesterday I was talking to my dad about progress on the family history, we were discussing his late brother Harve's children who all live in England and his uncle Earl whom I have been researching steadily for the past several months.  When kind of out of the blue he told me about a half brother he had that I never heard of before.  

Needless to say I was alittle surprise to discover this, I don't believe my father ever met this person although his brothers Harve and Keith had when they were children.

The only information that I have to go on is that his name is Macklin Brown, he was born sometime around 1920 but before 1923, in  possibly St. Lawrence, Jefferson or Lewis County New York. That he was raised; I believe by his paternal grandparents, (Brown) that he knew his mother; my grandmother and the circumstances which created his living situation. I don't know his fathers name nor his grandparents names.  I am assuming that he has in all likelihood passed away by now as he would be near 90 YOA if he was still alive. I am not sure that he stayed in New York State as an adult.  His mother, my grandmother died in 1938 and there is no indication of any connection with my fathers family after her death.

This one is likely to be a very difficult nut to crack, no census record have been located yet, newspaper articles or obituaries.  I have posted to the message boards in the affore mentioned Counties and Brown board seeking information and assistance.  

We shall just have to wait and see what information can be generated..............