In a very limited number of divorce mediations, one spouse feels the mediator favors the other spouse. In such a case resolution is unlikely to occur. If a spouse is concealing issues during mediation, the mediator cannot compel him or her to reveal such things as accurate assets or income. In contrast, an attorney can depose the spouse, require financial information or even counsel the client to hire a forensic accountant. Divorce mediators don’t have the authority a judge has, meaning the success of the mediation is wholly dependent on the cooperation between the parties.
Finally, parties may agree to continue child support past the statutory termination date. When this occurs, it is usually based on a mutual desire to support a child through college. Although the Court lacks jurisdiction to order child support beyond the statutory termination date, the Court does have jurisdiction to enforce a binding stipulation of the parties which provides for that.  If I am representing the obligor, I normally advise against this, because one can always support the children through college if one so desires. There’s no reason to get the Court involved.
You’ll also want to gather records for all income sources: paystubs, self-employment profit and loss statements, pension disbursements, social security, alimony and child support payments received. As for expenses, you’ll want to list your recurring expenses as well as ongoing liabilities, so that all mortgage payments, car loans, health insurance costs, food, utilities, student loans, credit card payments, etc. are known.