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 Jean de BeĢthencourt. They were married, but the date and place have not been found. They had no known children.
Her second husband was Mathieu de Bracquemont, who she married in BEF 1364. The place has not been found. They had no known children.