She was the daughter of Louise de La Vallière, born in secret. She was legitimized when her mother was made Duchess on 14 May 1667. The most beautiful of Louis XIV's daughters, she had a terrible wedding night with her husband, Prince of Conti Louis Armand de Bourbon, and had no children. She got smallpox and survived but passed it on to him and he did not. Her Wikipedia article is here.
According to Wikipedia, there were three living dowager Princesses of Conti alive at the same time. The dowager Princesses of Conti were given the name of Douairière (Fr. dowager) preceded by a number corresponding to their time of widowhood. Their full style would then be Madame la Princesse de Conti 'number' douairière. Between 1727 and 1732, there were three dowager Princesses de Conti:
• This princesse de Conti, Marie Anne de Bourbon (1666–1739), the legitimised daughter of Louis XIV and Louise de La Vallière; she was the wife of Louis Armand I, Prince of Conti. Widowed in 1685, she was known as Madame la Princesse de Conti première douairière. Her husband's title went to his younger brother, François Louis, Prince of Conti.
• Marie Thérèse de Bourbon (1666–1732), the wife of François Louis, Prince of Conti; widowed in 1709, she was known as ''Madame la Princesse de Conti seconde douairière.
• Louise Élisabeth de Bourbon (1693–1775), the wife of Louis Armand II, Prince of Conti, who was the son and successor of François Louis, Prince of Conti. Widowed in 1727, she was known as Madame la Princesse de Conti troisième/dernière douairière."