A.(1) "Split custody" means that each party is the sole custodial or domiciliary parent of at least one child to whom support is due. Split custody exists where there is a custody order or joint plan of implementation providing for split custody, or the court finds by a preponderance of the evidence that split custody exists.
(2) If split custody exists as set forth in this Section, each parent shall compute a total child support obligation for the child or children in the custody of the other parent, based on a calculation pursuant to this Section.
(3) The amount determined under Paragraph (2) of this Subsection shall be a theoretical support obligation owed to each parent.
(4) The parent owing the greater amount of child support shall owe to the other parent the difference between the two amounts as a child support obligation.
B. Worksheet A reproduced in R.S. 9:315.20, or a substantially similar form adopted by local court rule, shall be used by each parent to determine child support in accordance with this Section.