(a) Except as provided in subdivision (b), the existing parent or parents of an adopted child are, from the time of the adoption, relieved of all parental duties towards, and all responsibility for, the adopted child, and have no right over the child.
(b) The termination of the parental duties and responsibilities of the existing parent or parents under subdivision (a) may be waived if both the existing parent or parents and the prospective adoptive parent or parents sign a waiver at any time prior to the finalization of the adoption. The waiver shall be filed with the court.
(c) This section applies to all adoptions except intercountry adoptions governed by Chapter 4 (commencing with Section 8900).