In a proceeding to establish or modify child support or to establish an award for past support, there is a rebuttable presumption that the parental support obligation derived from the support guidelines is the amount ordered to be paid, unless support is established under section 2006, subsection 5 or section 2007. The court or hearing officer shall review the adequacy of a child support amount agreed to by the parties with reference to the parental support obligation.   [PL 2003, c. 415, §6 (AMD).]