Child support arrears include the interest, so the principal answer to your inquiry is yes. Put another way, you are not paying off "arrears balance . . . in full" if there still exists any interest. Generally the rate is 10% above the child support amount to pay for all arrears (principal and interest, from your terms). It is possible to negotiate a reduction in arrears, but it takes experience and some luck. As for the obligee (person receiving child support), it sounds as though your operative orders are incorrect and you should correct them through the court with a motion to modify. I suggest you seek the assistance of a Wisconsin licensed attorney that specializes in custody, placement and child support. You should be advised there is no connection between child support and placement; to connect or threaten any denial of placement rights because of the child support status is a potential felony. Good luck.
This answer is for informational purposes only. Please select "Helpful" and/or "Best Answer" if appropriate. Realize, by answering this question, no attorney/client relationship is created between the question poster and JCWB ESQ LLC. Although the response is an effort to assist, with the facts presented, it may not be appropriate and/or the best solution for your entire situation. The best way to handle any legal problem is to seek the advice of an attorney licensed in the jurisdiction where the issue arises.