Family Code – FAM § 7612
(a) Except as provided in Chapter 1 (commencing with Section 7540 ) and Chapter 3 (commencing with Section 7570 ) of Part 2, a presumption under Section 7611 is a rebuttable presumption affecting the burden of proof and may be rebutted in an appropriate action only by clear and convincing evidence.
(b) If two or more presumptions arise under Section 7611 that conflict with each other, or if one or more presumptions under Section 7611 conflict with a claim by a person identified as a genetic parent pursuant to Section 7555 , the presumption that on the facts is founded on the weightier considerations of policy and logic controls. If one of the presumed parents is also a presumed parent under Section 7540 , the presumption arising under Section 7540 may only be rebutted pursuant to Section 7541 .
(c) In an appropriate action, a court may find that more than two persons with a claim to parentage under this division are parents if the court finds that recognizing only two parents would be detrimental to the child. In determining detriment to the child, the court shall consider all relevant factors, including, but not limited to, the harm of removing the child from a stable placement with a parent who has fulfilled the child’s physical needs and the child’s psychological needs for care and affection, and who has assumed that role for a substantial period of time. A finding of detriment to the child does not require a finding of unfitness of any of the parents or persons with a claim to parentage.
(d) Unless a court orders otherwise after making the determination specified in subdivision (c), a presumption under Section 7611 is rebutted by a judgment establishing parentage of the child by another person.
(e) A person’s offer or refusal to sign a voluntary declaration of parentage may be considered as a factor, but shall not be determinative, as to the issue of legal parentage in a proceeding regarding the establishment or termination of parental rights.
(f) This section shall become operative on January 1, 2020.