This section applies only to a covered employee of a municipal corporation or a county who is subject to § 9–503 of this title and the dependents of those covered employees, unless the municipal corporation or county has made an election under § 9–683.6 of this subtitle. Except as otherwise provided in this subtitle, the Commission shall determine all questions of partial or total dependency in accordance with the facts of each case that existed: at the time of the occurrence of the accidental personal injury that caused the death of the covered employee; or on the date of disablement from the occupational disease that caused the death of the covered employee.