Legal Question in Family Law in California

There are some unlikely scenarios in which a step-father or person in a similar situation could seek reimbursement for support provided to a biological father's child. Generally there would have to be some kind of express or implied agreement, or request from the bio-dad that the other man provide support. The non-bio-dad's voluntary actions on his own initiative or only at the request of the mom would not likely give rise to any claims that would be successful in court. Otherwise support is entirely between the bio-parents and only they can claim against each other.