(1) Decrees under this chapter involving child custody, visitation, or child support entered in actions commenced prior to January 1, 1988, shall be deemed to be parenting plans for purposes of this chapter.
(2) The enactment of the 1987 revisions to this chapter does not constitute substantially changed circumstances for the purposes of modifying decrees entered under this chapter in actions commenced prior to January 1, 1988, involving child custody, visitation, or child support. Any action to modify any decree involving child custody, visitation, child support, or a parenting plan shall be governed by the provisions of this chapter.
(3) Actions brought for clarification or interpretation of decrees entered under this chapter in actions commenced prior to January 1, 1988, shall be determined under the law in effect immediately prior to January 1, 1988.