I believe this is a brief biographical sketch for her from here, "Saint-Aignan, Francoise Gere-de Rance, Duchesse de – (c1642 – 1728)
French aristocrat and courtier
Francoise Gere-de Rance was known as Madamoiselle de Luce before she became the second wife (1680) of Francois Honorat de Beauvilliers, (1607 – 1687), Duc de Saint Aignan, and attended the court of Louis XVI and Madame de Maintenon at Versailles. She survived her elderly husband for over thirty years (1687 – 1728) as the Dowager Duchesse de Saint-Aignan and died in the reign of Louis XV. The duchesse was mentioned in the correspondence of the British antiquarian Horace Walpole. She was the stepmother of Paul de Beauvilliers (1648 – 1714), second Duc de Saint-Aignan and Duc de Beauvilliers.