The grown-ups are, from left to right, the comtesse de Provence, the comte de Provence, King Louis XVI, Queen Marie Antoinette, the comtesse d’Artois, the comte d'Artois, and madame Élisabeth. The girl kneeling at the dauphin’s feet is madame Thérèse, the future duchesse d’Angoulême.
The picture was apparently exhibited in 1782, but the event occurred in 1781.
Upgrade image from Wikimedia replaces another version posted 8 January 2011 to the Subalbum for Marie Therese de Savoie, comtesse d’Artois (here); there is at least one other left-to-right listing of those in the portrait than that accompanying this image in Wikimedia that is used here.
From Wikimedia.