Can Child Support Be Established After Being Initially Declined In The Divorce Decree? (ks/ny)

Ex-husband (NY) went back on verbal agreement. Still have a minor (KS) in my care. I requested that he continue payments after he stopped a few months ago without warning. He has told me that there is nothing in the decree saying he owes anything, and that he will not be paying for our child any more.

He has had zero contact with either of our children for over a decade. The only 'contact' is the 'under the table' payments.

I was young and uninformed with a HS diploma when I signed the decree and had no reason to believe he (a-soon-to-be attorney, recently accepted to an Ivy League law school and filed our divorce paperwork himself) wouldn't fulfill his verbal agreement- indeed he has kept up with the agreement for roughly a decade, until now.

Can I now request an initial order for child support to be established, even though I signed that zero funds were required in the initial divorce decree?