( October 14, 2024, 1:34 PM EDT) -- GREENSBORO, N.C. — A plaintiff dental hygiene company cannot amend its trademark infringement complaint to add an allegation that defendant companies that make similar products also infringed on the plaintiff company’s copyright, along with other allegations, a federal magistrate judge in North Carolina held Oct. 11, saying that granting the motion would be prejudicial to the defendant companies....