No amendment of any petition or of any answer may be made except on leave granted by the appropriate Hearing Committee Chair. Whenever, in the course of a formal hearing, evidence shall be presented upon which another charge or charges against respondent might be made, it shall not be necessary to prepare or serve an additional petition with respect thereto, but upon motion by respondent or by Bar Counsel, the Hearing Committee Chair may continue the hearing. After providing respondent reasonable notice and an opportunity to answer, the Hearing Committee may proceed to the consideration of such additional charge or charges as if they had been made and served at the time of service of the original petition.