Have you ever dealt with a friend who refused to pay child support?

A run-down of the situation:

I have a couple of friends who had a child together accidentally a few years ago. Mom is the custodial parent. Dad is refusing to pay child support. The child support is not court-mandated though Mom is getting to that point and dad paid until a few months ago. Mom is working full-time and while the child is healthy, well-fed, sheltered and clothed, Mom is eating less and less and even goes some days without food so that her daughter may eat. Still, Dad refuses to pay child support.

There’s not really anything I can do at the moment, so I’m just wondering how other Jellies have dealt with friends who refused to pay child support.