Is bio father liable for child support?

Yes I agree that a discussion that grows out a question like this should stay together.

I'm not sure the OP has handled this pretty well. I believe I can understand his ire and don't fault him for it. I would probably be as angry as he appears to be if the situation was reversed. But I would like to believe I would put the innocent victim of this debacle, his son, first. Consider his well being before I consider revenge against the people who betrayed both him and myself. And that's where I think the OP has come up short.

This site doesn't just answer questions. We try to provide the best solution to a problem. Often we get asked a question where the simple and straightforward answer is not the solution to the problem. We like to go that extra step. Sometimes, we wind up putting an OP's nose out of joint in doing so, but you don't make an omelet without breaking some eggs.

Scott-it is about Setting Aside or Vacating Judgment of Paternity.The OP has never been adjudicated as a father.The correct articles are:
7540. Except as provided in Section 7541, the child of a wife
Cohabiting with her husband, who is not impotent or sterile, is conclusively presumed to be a child of the marriage.
7541. (a) Notwithstanding Section 7540, if the court finds that the conclusions of all the experts, as disclosed by the evidence based on blood tests performed pursuant to Chapter 2 (commencing with Section 7550), are that the husband is not the father of the child,the question of paternity of the husband shall be resolved accordingly.

(b) The notice of motion for blood tests under this section may be filed not later than two years from the child's date of birth by the husband...

BTW it does not change the result.

Yes-if you will be able to transfer the case to Tn,Ga or Oh.
In California-no! It is not unheard a child to know that s/he has a "false" father who pays child support and alimony , and a "true dad" , who plays daddy every day.

Wondering when you were going to weigh in on this one . So, since the child is 8, then the window of opportunity has passed, correct?

It may or may not have passed. The limitation is based upon "knowing" and if there was no way of knowing before then it may be possible to revisit the issue after the expiration date. Since he is claiming he was told the child was his and he nad no reason to suspect otherwise and now he does then the clock may start ticking then. 2 years from the date he first found out.