WASHINGTON, Dec. 11 (TNSFR) -- The International Trade Commission has allowed an update to a key trade investigation, opting not to review a decision that grants a motion to amend the complaint and notice of investigation filed by Syensqo SA, Brussels, Belgium, Solvay Specialty Polymers USA LLC, Alpharetta, Georgia, and Solvay Specialty Polymers Italy SPA, Bollate, Italy. This probe concerns the alleged unlawful importation and sale of certain polyvinylidene fluoride resins in the U.S.