Complex sentence: The two counties remained separate until 1974, when they were merged as the Regional Municipality of Haldimand-Norfolk on the advice of a report by Milt Farrow, a "special advisor" appointed by the Government of Ontario.
Split into simpler sentences: The two counties remained separate until 1974, when they were united as the Regional Municipality of Haldimand-Norfolk. The merger came following the report of Milt Farrow, a "special advisor" appointed by the Government of Ontario.