California Code, Family Code - FAM § 9303

(a) Except as permitted by the court, upon a finding of good cause, a person shall not adopt more than one unrelated adult pursuant to this part within one year of the person's adoption of an unrelated adult unless the proposed adoptee is the biological sibling of a person previously adopted pursuant to this part or unless the proposed adoptee is disabled or physically handicapped.An order finding good cause shall be in writing or stated on the record.

(b) Except as permitted by the court, upon a finding of good cause, a person shall not adopt an unrelated adult pursuant to this part within one year of an adoption of another person pursuant to this part by the prospective adoptive parent's spouse unless the proposed adoptee is a biological sibling of a person previously adopted pursuant to this part.An order finding good cause shall be in writing or stated on the record.