You don't get to receive any benefit from your ex's parents' generousity to him. His children could benefit if they spend more time with him, but you don't get it.

The only way this could affect your child support would be if he decided to quit his job becasue he doesnt' have to work any more because the inheritance made him flush. THEN the courts would say that they will attribute his income to be the same as his previous income because he's not allowed to voluntarily reduce his income for the purposes of child support just because HE no longer needs th eincome. The courts would say the KIDS still need the income so he couldn't reduce his support just because his family is not paying for his lifestyle.

Of course, if his mother was Ivana Trump and left billions of dollars worth of stuff, the judges' would probably try to find a way to give you some just because the celebrity and extreme nature of the situation would make them want to treat you differently. But that would not be under any theory of how the law works, it'd just becasue their general sense of fair play would not have you living hand to mouth while your ex lives off a billion dollar estate.

Think of it, if your own parents died and left you with a house and property, should he be allowed to pay you LESS support just because YOUR parents were so generous? OOOOR, if you marry a rich man as your next husband, will that mean your children's father should not pay support for them because the rich man has enough money that your ex thinks that your new husband should support your first husband's kids?