Trying to find possible half-sibling
My father may have a child from a previous relationship with. He is still alive and will likely deny knowledge of this. I have his birthdate, but don't have his SS#. How do I go about finding out whether his name is listed on some birth certificate (most likely in NY State - Buffalo or Syracuse, NY area)? Years of child's birth are likely between 1968-1975. I also suspect that he gave up all rights to this child- mother had full custody (whether it was optional or court mandated). Is there any way to find records of that for the same time?