In 1726, Diane Adélaïde's oldest sister, Louise Julie, wed her cousin, Louis Alexandre de Mailly, comte de Mailly. Shortly thereafter she caught the attention of King Louis XV, and was permitted by her husband to become a royal mistress.
In 1738, she received a letter from her younger sister Pauline-Félicité requesting to be invited to court. Louise Julie granted her sister's wish, but upon her arrival at court, Pauline-Félicité seduced the king and became his mistress.
While Madame de Mailly remained as the official mistress, the king fell in love with Pauline-Félicité and arranged for her to marry the marquis de Vintimille.
Afterwards, the king's best friend, the manipulative duc de Richelieu, began to cast about for another candidate to fulfil his royal friend's desires as he did not want Madame de Mailly to regain the king's affections. He eventually decided upon the younger sister of both Madame de Mailly and Madame de Vintimille, Marie Anne, the widow of the marquis de La Tournelle.
But Madame de La Tournelle, who was by far the ablest as well as the most attractive of the de Nesle sisters, unlike Madame de Vintimille and Madame de Lauraguais, was by no means disposed to rest content with a divided empire and secret favours. She insisted that her older sister Madame de Mailly should be dismissed and she herself acknowledged in her place. Louis, who was already wearying of the tears and reproaches of the elder sister, consented; and the countess's post of dame du palais to Queen Marie Leszczyńska was taken away from her, and she was ordered to leave the court. Throughout the war over the king's affections between Madame de Mailly and Madame de Châteauroux, Madame de Lauraguais sided with Madame de La Tournelle.
It was rumoured at the time, that one way that the new duchesse de Châteauroux kept the interest of the king was to periodically offer him a ménage à trois with her sister, Madame de Lauraguais. That Madame de Lauraguais actually began sleeping with the king at this point, however, is debatable.
Directed by Richelieu, himself dominated by Madame de Tencin, Madame de Châteauroux tried to arouse in the king a greater sense of leadership, dragging him off to the battlefield and encouraging him to form an alliance with Frederick II of Prussia, in 1744. Her political role was great, despite that it was exerted from behind the scenes. During Madame de Châteauroux's frequent journeys to and from the king as he warred, she was accompanied by Madame de Lauraguais. Besides being an amiable companion, Madame de Châteauroux did not consider her simple sister much of a rival.
After successfully surviving a disgrace provoked by the king's illness at Metz, Madame de Châteauroux's victory did not last long, for she died unexpectedly on 8 December 1744. After her death, the king for a short time consoled himself with her sister, Madame de Lauraguais. A few months later, however, the king already had a new mistress, Madame de Pompadour.