(a) Amendments. (1) By right: The Department may amend its complaint without leave at any time within 30 days of the date the complaint is filed or at any time before respondent's responsive pleading is filed, whichever is later. Respondent may amend its answer without leave at any time within 30 days of filing of its answer. A party shall plead in response to an amended pleading within 15 days of receipt of the amended pleading.

(2) By leave: Upon conditions as are necessary to avoid prejudicing the public interest and the rights of the parties, the hearing officer may allow amendments to pleadings upon motion of any party.

(3) Conformance to evidence: When issues not raised by the pleadings, but reasonably within the scope of the proceeding initiated by the complaint, are tried by express or implied consent to the parties, they shall be treated in all respects as if they had been raised in the pleadings, and amendments of the pleadings necessary to make them conform to the evidence shall be allowed at any time.

(b) Supplemental pleadings. The hearing officer may, upon reasonable notice, permit service of a supplemental pleading concerning transactions, occurrences, or events that have happened or been discovered since the date of prior pleadings.