What rights does a birth mother have to a prospective adoptive parent who has never consented to an adoption?

Where the birth mother has never consented to an adoption, the prospective adoptive parents have no constitutional or statutory right to maintain a parent-child relationship. For the six-months' duration of the AD 22 form, the prospective adoptive parents' "temporary physical custody [is] permissive, but their retention of the child [becomes] unlawful when they refuse[ ] to return the child upon [the birth mother's] request." (Rogers v. Platt, supra, 199 Cal.App.3d at p. 1213, 245 Cal.Rptr. 532.)