Like in your situation, I was looking for living relatives in Erie County, PA. By using the phone directory, I obtained the first names and addresses of prospective relatives. Several months went by, after which I received two responsess to my self addressed and stamped envelopes that I had enclosed with my cover letter.
This led to two hits. One was my great grandfather's grandaughter and the other had to do with a cousin that I had not known about.
You might want to give that a try. It worked for me.
PS Don't let the "Flag" discourage you. Just take the path you want to take.