(14) Computation of child support. (a) Except in cases of shared physical care or splity physical care as defined in subsection ( and (9) of this section, a total child support obligation is determined by adding each parent's respective obligations for the basic child support obligation, work-related net child care costs, extraordinary medical expenses, and extraordinary adjustement to the schedule. The parent receiving a child support payment shall be presumed to spend his or her total child support obligation directly on the children. The parent paying child support to the other parent shall owe his or her total child support obligation as child support to the other parent, minus any ordered payments included in the calculations made directly on behalf of the children for work related net child care costs, extraordinary medical expenses, or extraordinary adjustments to the schedule.