An agreement between parents or between parents and third parties respecting a child’s upbringing cannot oust the statutory obligation of a court to grant a custody order that reflects a full and balanced consideration of all factors relevant to a determination of the child’s best interests. A prior parenting agreement between the disputants is only one factor to be considered, albeit an important factor.237As Nightingale J, of the Ontario Superior Court of Justice, remarked in Todoruck v Todoruck, "a parent who has agreed to a child care arrangement should be prepared to explain why what he or she felt was appropriate earlier on is no longer appropriate."238Parents cannot oust
the statutory jurisdiction of the court to order child support and access by contracting to trade off child support and access.239Although a separation agreement may include provisions whereby its terms shall only be varied in the event of a material change of circumstances, such provisions cannot oust the jurisdiction of a court to grant orders for custody and child support in subsequent divorce proceedings. In allowing an appeal in Jay v Jay240because the chambers judge had erred by concluding that his jurisdiction under the Divorce Act was limited by the provisions of the separation agreement, the Appeal Division of the Prince Edward Island Supreme Court expressed the following opinion:
Irrespective of the terms of any agreement between the parties, the court has the jurisdiction in a motion for corollary relief in connection with divorce proceedings to hear and deal with all issues of custody and child support. An agreement between the parties is only one factor to be taken into consideration when deciding upon the best interests of the child. While such an agreement provides strong evidence of what the parties accepted at the time as meeting the best interests of the child, it does not relieve the court of its responsibility under s 16 of the Divorce Act to make an independent assessment of the best interests of the child. (See: Willick v. Wil-lick,  3 S.C.R. 670.)241In the context of custody and access orders, the above observations are clearly consistent with established caselaw and with the express provisions of section 16(8) of the Divorce Act whereby "[i]n making an order under this section, the court shall take into consideration only the best interests of the child of the marriage as determined by reference to the condition...