I THINK I CAN HELP! (At least point ya in the right direction!!!) It's been many years since you've posted this on this ancestry.com board, so I hope you will still get this. Hopefully your search has been successful in the intervening yrs, but if not you may find this useful:

My grandfather was Sidney Wiley Abel II of Macon, Bibb Co., GA. His father was S.W. Abel Sr. (naturally) - I noticed you weren't 100% sure of the name "Cecil", but possibly phonetic similarity to "Sidney"? My grandfather's mother's name WAS Ethel - so it seems to be a strong connection for whom you're searching. Interestingly, my grandmother affectionately called my granddad "Pat"! She was the only one I ever heard call him that as well; vaguely recall he said it was an old nickname from his Army days when I asked him why she called him Pat, instead of Sid or Sidney. I believe the only sibling to my granddad and your father [note: I never heard him refer to any of his brothers as Cliff/ord, though I believe I did hear "James" when he spoke of his siblings.] still living is Annie, who is living in Rome, GA (married name of Shannon, husband Virgil). Annie is the sweetest lady & she's kept a detailed family history that would likely help point you in the right direction! All my findings of the S.W. & Ethel Abel family of Macon, GA has shown them to be community pillars, generously kind and highly respected. If you get this message and believe this is the family for whom you are searching to find your half bro/sis, send a message back to me and I'll get Annie Abel Shannon's contact information for you. I'd love to help if you haven't had a fruitful search! And, of course, it's a pleasure to meet another member along the family line!!! [2nd/3rd cousin I believe?]

Look forward to hearing from you if you still need this!

C. Abel