Any such complaint may be amended upon such terms as may be deemed just, prior to the hearing, by the regional director issuing the complaint; at the hearing and until the case has been transferred to the Board pursuant to Sec. 102.45, upon motion, by the administrative law judge designated to conduct the hearing; and after the case has been transferred to the Board pursuant to Sec. 102.45, at any time prior to the issuance of an order based thereon, upon motion, by the Board.