If he was injured at work he will be paid a finite amount of money based on the degree of injury that will be determined when he is declared able to return to work, or when he has reached the maximum medical improvement he is expected to reach. It will not, except in very special circumstances, be a whole whole lot of money. We're not taking about millions of dollars here.
If you're not receiving support for these children, then you need to take care of that. Money hungry mom will not be able to decide whether or not her son pays child support to support his children.