ex is taking a voluntary buy-out from his company. What happens to my child support.

My ex is taking a voluntary buy-out from his company in which he will be given a lump sum. He is currently ordered to pay 800 per month in child support and also to carry our daughter on his medical insurance. The company has told me (because I'm an employee there as well) that they will only pay the $400 on that lump sum payment. And also that he can file for unemployment right away. I'm concerned about this because he will not get much if he files for unemployment and I'm afraid he may claim this as his only income and the child support would be dropped down considerably. And then he would be sitting on this buyout money. This is not something he has to do. He survived the layoffs on our job but our company is offering buyouts to anyone who wants to take one. So he is volunteering to quit his job. He would owe me 8 thousand dollars from this buyout money for child support. How can I make sure he does that and that the courts know about this lump sum?