Marie Françoise Catherine de Beauvau, Madame de Boufflers, was one of 19 siblings. She married Louis François de Boufflers (1714–1752), marquis d'Amestranges, and bore him Stanislas de Boufflers, later famous as a poet. Her Wikipedia article is here.
Photo - René-Gabriel Ojéda; some spots in background removed with Photoshop and size increased by half and darkened by gogm.
Mlle. Thérèse wears a better looking coiffure than Madame's typical colonnade of curls. beth wear shoulder-length sleeves, Madame's with downward flared engageantes and Mlle. with forward and back flared engageantes. Both wear gloves and dresses with panniers.
Keywords: 1768, Carrogis, Madame de Boufflers, high curly coiffure, cap, high straight coiffure, floral headdress, square neckline, ruffles, stomacher, revers, elbow length close sleeves, bows, engageantes, forward-back flared engageantes, panniers, over-skirt, ruching neck band, gloves