In 1333, her father issued an inheritance law, which said that after his death, the County of Cleves should fall to Margaret and her sisters Elisabeth and Maria.
Her eldest son, Engelbert III succeeded as Count of the Marck.
After her father, Count Dietrich VIII of Cleves, died on 7 July 1347, Margaret and her sons Engelbert III and Adolf III tried to secure the Cleves territory.
After his death, the Count of the Marck could finally assert their right to inherit Cleves.
Adolf succeeded as Count, her third son Dietrich received most of the holdings on the right bank of the Rhine.