Rule 15. Amended and supplemental pleadings.

(a) Amendments. - A party may amend his pleading once as a matter of course at any time before a responsive pleading is served or, if the pleading is one to which no responsive pleading is permitted and the action has not been placed upon the trial calendar,  he may so amend it at any time within 30 days after it is served. Otherwise a party may amend his pleading only by leave of court or by written consent of the adverse party; and leave shall be freely given when justice so requires. A party shall plead in response to an amended pleading within 30 days after service of the amended pleading, unless the court otherwise orders.

(b) Amendments to conform to the evidence. - When issues not raised by the pleadings are tried by the express or implied consent of the parties, they shall be treated in all respects as if they had been raised in the pleadings. Such amendment of the pleadings as may be necessary to cause them to conform to the evidence and to raise these  issues may be made upon motion of any party at any time, either before or after judgment, but failure so to amend does not affect the result of the trial of these issues. If evidence is objected to at the trial  on the ground that it is not within the issues raised by the pleadings, the court may allow the pleadings to be amended and shall do so freely when the presentation of the merits of the action will be served thereby and the objecting party fails to satisfy the court that the admission of such evidence would prejudice him in maintaining his action or defense upon the merits. The court may grant a continuance to enable the objecting party to meet such evidence.

(c) Relation back of amendments. - A claim asserted in an amended pleading is deemed to have been interposed at the time the claim in the original pleading was interposed, unless the original pleading does not give notice of the transactions, occurrences, or series of transactions or occurrences, to be proved pursuant to the amended pleading.

(d) Supplemental pleadings. - Upon motion of a party the court may, upon reasonable notice and upon such terms as are just, permit him to serve a supplemental pleading setting forth transactions or occurrences or events which may have happened since the date of the pleading sought to be supplemented, whether or not the original pleading is defective in its statement of a claim for relief or defense. If the court deems it advisable that the adverse party plead thereto, it shall so order, specifying the time therefor. (1967, c. 954, s. 1.)