How can I change a Final Order of the Court in Ontario?

A Final Order under either the Divorce Act or the Family Law Act may be varied/changed if either parent can demonstrate a material change in circumstance that, if known at the time, would have likely resulted in a different order. The variation/change must be sought in the Court that granted the original Order. If a support order or agreement has been assigned to a person or an agency pursuant to the Final Order, the parties are required to serve the assignee as if the assignee were also party to the proceeding.