a. Amendments to pleadings. A party may amend a pleading one time within twenty-one (21) days after service of a responsive pleading. If no response is required, a party may amend a pleading within twenty-one (21) days after the pleading was filed. If a motion is filed under Rule 116(a)(2)(iv), (a)(3) or (a)(4), a party may amend a pleading one time before the date on which a response to the motion is due. However, the filing of an amended pleading before the response to such a motion is due does not, by itself, relieve a party opposing the motion from filing a timely response to the motion. Thereafter, and upon a party's motion, the court may permit the filing of an amended pleading at any stage of the proceeding and on terms that are just. Leave to amend must be freely given when justice requires. A party must file a response to an amended pleading within the time remaining for the party's response to the original pleading, or within twenty (20) days after service of the amended pleading, whichever is greater. [ARCP 15(a)]

b. Amendments to conform to the evidence. When a party raises issues at trial that were not stated in the pleadings, the court may rule that the pleadings are conformed to the evidence and decide the matter based on the facts presented at trial. If a party objects to the introduction of evidence at trial on the ground that the evidence is not relevant to the pleadings, and the objecting party would be prejudiced by going forward, the court may grant a continuance to enable the objecting party to conduct discovery concerning the evidence, or the court may decline to admit the evidence. [ARCP 15(b)]

c. Relation back of amendments. An amended pleading may relate back to the original filing date if the claim or defense asserted in the amended pleading arose out of the conduct, transaction, or occurrence that is described in the original pleading. An amended pleading changing the party against whom a claim is made relates back if: the previous requirement is met; if the new party received notice of the action within the time required by law for bringing the action and will not be prejudiced by the belated filing; and if the new party knew or should have known of a mistake concerning the identity of the proper party in the original pleading. [ARCP 15(c)]

d. Supplemental pleadings. Upon motion, the court may permit a party to file a supplemental pleading that contains claims or defenses that have arisen since the date of the original pleading. If the court decides that the filing of a supplemental pleading is appropriate, it may also order the opposing party to file a response to the supplemental pleading, and set a time for the opposing party to file a response. [ARCP 15(d)]