The commission, at any time prior to its determination, may for good cause allow or require amendments to the notice of formal proceedings and may allow amendments to the answer. The notice may be amended to conform to proof or to set forth additional facts, whether occurring before or after the commencement of the hearing. In case such an amendment is made, the judge shall be given reasonable time both to answer the amendment and to prepare and present a defense against the matters charged thereby.
SDCL tit. 16, ch. 1A, app TO CHAPTER 16-1A, III, 12