19 C.F.R. § 210.57
A motion for temporary relief may be amended at any time prior to the institution of an investigation. All material filed to amend the motion (or the complaint) must be served on all proposed respondents and on the embassies in Washington, DC, of the foreign governments that they represent, in accordance with § 210.54 . If the amendment expands the scope of the motion or changes the complainant's assertions on the issue of whether a bond is to be required as a prerequisite to the issuance of temporary relief or the appropriate amount of the bond, the 35-day period under § 210.58 for determining whether to institute an investigation and provisionally accept the motion for temporary relief shall begin to run anew from the date the amendment is filed with the Commission. A motion for temporary relief may not be amended to expand the scope of the temporary relief inquiry after an investigation is instituted.
19 C.F.R. § 210.57