First for your safety, you shouldn't post your phone number.

You might try: http://registry.adoption.com/index.php

As a retired long term career in law enforcement, I would whole-heartedly recommend you go through a professional. Someone licensed if possible. If not licensed, at least someone that can handle their own safety, security and potential lawsuits, other than a well meaning person with genealogy interest.

I don't know if this is a divorce issue, or what, but, be very careful when trying to find lost family. The father may be just fine, or there could be a history of criminal records, drug/alcohol addictions, mental illness, etc. Or the children of this person could have criminal records, drug addictions, mental illness. The siblings may not want an "outsider" to come into the picture.

Ask someone in your family for information or help.