Legal Question in Family Law in California

He may be a presumed father under the doctrine of parentage by estoppel. You need to consult with a competent family law attorney who is thoroughly familiar with California's quirky paternity laws.

Mr. Roach is exactly right. It is possible that he could be deemed responsible as if he had adopted the child. Such cases are based on fairly obscure law, and will depend on a detailled examination of the facts. So there really is no way to get a good answer to your question without spending time with an attorney one on one.