Louise-Adelaide de Bourbon-Penthievre (1753-1821) Duchess of Chartres Joseph Siffred Duplessis (1725-1802)

The picture has something of this: people, woman, girl, water, reclining, nature, river, baby, dress, tree, wear, nymph, grass, peace.
Perhaps it’s a painting of a woman in a white dress sitting on a rock next to a body of water with a sailboat in the water behind her.