(1)  Subject to subsection (2) , an application for an adoption order shall be made by the Secretary or the principal officer of an approved agency on behalf of the prospective adoptive parents.

(2)  Where–

(a) a prospective adoptive parent is a spouse of a natural parent or of an adoptive parent of the child proposed to be adopted; or

(b) a prospective adoptive parent is a person who is, or whose spouse is, a relative of the child proposed to be adopted–

only the Secretary is competent to make the application on behalf of the prospective adoptive parent.