Isabeau was the daughter of unknown parents. The date and place of her birth have not been found.
She had two marriages/partners. Her first husband was Mathieu IV de Roye. They were married, but the date and place have not been found. They had no known children.
Her second husband was Guillaume II Cassinel. They were married, but the date and place have not been found. They had no known children.
Note 1
Daughter of Gaucher de Châtillon and Marie de Coucy