If a person believes they are not the parent of a child, or if they don't have proof of the parentage of the child, they can apply to the Family Courts for a declaration of parentage.
The court can order a DNA test to determine parentage of the child, and the results are viewed by the court as conclusive evidence of parentage for child support purposes. The court is then able to make an order to start or end a child support assessment.
For more information about parentage go to The Guide.