Ordinarily yes. Time spent in the United States in lawful status for a related entity of the same employer does not interrupt the continuous year abroad, though it also cannot be counted toward it. The qualifying twelve months must therefore be located within her Canadian service, inside the three years before filing.
Not interruptive, and not creditable either
The rule solves one problem and creates another. It solves the fear that a secondment destroys eligibility: Marguerite's eight months in Maine, worked in lawful status for a company related to her employer, leave her earlier Canadian employment intact as a continuous block. It creates an arithmetic problem, because those months add nothing, so the three-year lookback effectively contains less usable Canadian time than the calendar suggests.
Where several trips are spread across the period the counting becomes genuinely technical and should be done on documents rather than memory: entry and exit records, assignment letters, payroll records and expense claims all help establish where she was. Two other conditions have to hold at the same time. The year relied on must itself have been managerial, executive or specialised-knowledge employment, and the Canadian and American entities must stand in a qualifying relationship with both actively doing business.