When my ex wife and I reverse custody of our child will I be able to waive child the child support that she may owe

If I understand your post/question correctly, it sounds like you and your ex have entered into a post divorce agreeement for your child to come and live with you and which you will no longer be paying child support. In addition, you have raised the question of whether your ex is going to be obligated to pay child support in reverse, and whether you can agree to "hold open" child support from her. You cannot terminate or waive child support under Wisconsin law, but you can agree to have it "held open." This means that you would have the right to back into court to ask for child support in the future, if there was a change in circumstances of a substantial and significant nature. Your agreement on this still however, must be approved by the court and the court may or may not approve a stipulation as to holding child support open. You will need to spell out in the agreement the reasons why you are both asking the court to hold it open as the court must make specific findings why the child support guidelines are not being followed. Any family law agreement, pre-judgment or post judgment, must be submitted to the court for approval and are not binding until the court approves the same.