I’m familiar with child support rules in Illinois, and, to a lesser extent Ohio. Both states have rules that would not take the child’s wealth into account in the standard calculation. Illinois–and I think Ohio–would allow for a “downward deviation” if the standard formula produces an unreasonable result or a windfall for the child. Such downward deviations are in the court’s discretion, and so are not predictable in the way the basic support rules are. However, a child’s independent wealth, especially if the parent owing support had little income, sounds like a plausible basis for a downward deviation. Other states might handle this differently, but neither Illinois not Ohio are unusual in their handling of child support.