This cannot, and should not be the goal of child support. It’s mathematically impossible to reach that goal when one has more than one BM.
The courts shouldn’t be dictating morality. They should only be ensuring that the child has enough reasonable financial support from the non-custodial parent. Future might be a shyt human being for having the means and choosing not to send his kids to the best private schools, but it’s not the government’s place to mandate that he does. And they know this, that’s why they set an amount without dictating how the custodian parent has to spend it.