Modifying a final decree of divorce with children and modifying a final order in a suit affecting the parent-child relationship are identical processes. You can pursue a modification in the event of a material and substantial change in circumstances. In regards to child support specifically, a modification is permissible after 3 years without regard to a material change in circumstances so long as the new support amount would vary by 20 percent or $100.00.
When considering a modification, the Courts rarely consider evidence from prior to the previous order or date of the mediated settlement agreement, which defined the terms of the final order. There are exceptions such as demonstrating a continuing pattern of behavior, but as a general rule, the Court will focus on the specific window of time since the last order was put in place. Other than this limitation, pursuing a modification is similar to establishing the initial order. The sections of this website related to conservatorship (parental rights), child support, and visitation can provide specific information on the terms of the order that you may be interested in modifying.
I encourage you to give me a call to discuss a modification that you may be considering, I would be happy to speak to you regarding the possibility of a modification free of charge.