Can my ex-spouse reduce child support payments because he’s having another child with his new spouse?
No, he cannot reduce the payments unless you both agree or he goes to court and a judge sets a different amount. The judge will likely use the Child Support Guidelines. This means the amount will depend mainly on your ex-spouse's income and how many children the support is for. The fact that he is having another child with someone else is usually not, by itself, a reason for the judge to change the amount.