When the family of 4 in Leduc, Alberta began their morning commute on that clear day in March 2024, the underinsured commercial truck operator who would collide with them carried $200,000 in third-party liability coverage on his vehicle. From his vantage point as the tortfeasor, that limit represented the full extent of his insurable obligation to compensate anyone he might injure through negligent operation of his truck. He had purchased what he understood to be adequate coverage for a commercial vehicle, had paid his premiums faithfully, and had no reason to contemplate the complex web of insurance products that might sit behind any vehicle he encountered on Alberta's highways. Yet the collision he caused that morning would expose him to a coverage architecture he had never considered: the family's $2 million SEF 44 limit and their $1 million umbrella limit, products designed precisely for moments when operators like him carry insufficient insurance to make injured parties whole. Understanding how priority of payment operates between these coverage forms requires examining the tortfeasor's exposure from the outside looking in, recognizing that the injured family's insurers will step into a carefully sequenced payment hierarchy that ultimately determines how much of the $1.2 million in damages flows from which policy, and in what order.