This chapter shall not apply to the granting of visitation rights to the natural grandparents of any child who has been adopted by order or decree of any court unless: (a) one (1) of the legal parents of such child is also a natural parent of such child; or (b) one (1) of the legal parents of such child was related to the child by blood or marriage prior to the adoption. This chapter shall apply to persons who become grandparents of a child by virtue of adoption.