CCP 1155     

Art. 1155.  Supplemental pleadings

The court, on motion of a party, upon reasonable notice and upon such terms as are just, may permit mover to file a supplemental petition or answer setting forth items of damage, causes of action or defenses which have become exigible since the date of filing the original petition or answer, and which are related to or connected with the causes of action or defenses asserted therein.