Support is not based on the time the custodial parent has the child but to insure there is a home for the child to return to after visitations as well.
If primary custody has changed since the time of your divorce, with your having your children substantially more than was contemplated in your divorce decree, you should return to court to address whether the change is substantial enough to warrant a modification. You should not be paying support for the right to be raising the child.
At the same time you can repair the problem of which school is proper for the children. If non-custodial parent has taken over full-time parenting, except for the now reversed visitation schedule, and the kids are still going to the court ordered custodial parent’s local school system, the parents are setting themselves up for problems. If the parents had each located themselves in different towns after the divorce, the kids would now be going to the school far from where they presently live most of the time. That isolates them from friends they make at school. It also makes getting them to and from school a logistical nightmare. The kids should be going to school where they primarily live.
Parents need to return to court and fix the chaos they have created in their children’s lives by failing to follow the plan they set out in their divorce agreement. Refusing to do so puts the children in the middle and at risk. This is contrary to everything taught in parenting courses the court requires divorcing parents to take. The cost of returning to court to repair the gaps created over time is less than the long term negative impact on your children’s lives.