Paying Child Support With Son's Bank Account

by Miller
(Illinois)

My ex fiancee has full custody of my son. She has called my grandparents and family members for more money. Claiming I have never paid her. It is automatically deducted out of my paycheck. When she receives money from my family she buys stuff for herself and not my son. So I would like to know if there is a way that I can put the money in my son's account where she can not touch it and only give her a set amount where she can buy the necessities he needs. Any information pertaining to this in the Illinois state laws would be greatly appreciated.