La. C.C.P. art. 1155. — Supplemental pleadings

The court, upon written consent of the parties, may permit the mover to file a supplemental petition or answer setting forth items of damage, causes of action or defenses that have become exigible since the date of filing the original petition or answer, and that are related to or connected with the causes of action or defenses asserted therein. If the parties do not consent, the court may grant leave to file a supplemental petition or answer only upon contradictory motion.