To change custody arrangements after a divorce is finalized, you have to prove a substantial change in circumstances affecting the child’s welfare. The court also wants to see that modifications are in the best interest of the child. Employment change, remarriage, health of parents and other adults involved in care, and drug or alcohol abuse are a few factors that the court might consider to be disrupting the child’s stability. A motion must be filed with the court to modify child support. If an agreement can’t be reached by the parents, the court will hold a hearing to review the modification.