Sarah-- I'm guessing that when you mention "her birth ceritficate" you actually mean "his," meaning your father's, since if you had HER birth certificate, it would have her parents names on it and problem would be solved.
Let me ask a couple of questions. We need to try and narrow down a place, if possible. Where was your father born? Your uncle? Where/when were Betty Jo and Curtis married?
How is Great-uncle Delaney connected...her paternal grandfather's brother, yes? Where were they when you found them on (which?) census? This great uncle may be your greatest lead. How did you find out about him?
What was the date of death on the OKC SSI record? There's always a chance of an obituary. But frankly, I find it very hard to believe she stayed with her maiden name. Especially since she used several maiden names. I'm betting she remarried and therefore that OKC record is probably someone else. But, definitely worth a look.
Do you know the mother's first name or Harradine's first name? The other husband's (#2) name? When you say "She hada sister Bonnie" was this Betty Jo's sister or Betty Jo's mother's sister (Betty Jo's aunt)?
I will prowl around some of my sources, but if we can narrow down an area, the chances for success increase greatly.