Princess Sophia Wikipedia article is here. She never married, but did have affairs. It was alleged she bore an illegitimate child. Like Princesses Beatrice and Victoria afterwards, she was obliged to stay with her mother, Queen Charlotte, who was isolated by King George III's mental illness. According to her Wikipedia article, Princess Amelia was taken by tuberculosis.

Princess Sophia (1777-1848), three-quarter-length, in a black dress with white gauze sleeves and a white shawl embroidered with poppies, seated by a pillar, Windsor beyond by Robinson after Sir William Beechey (auctioned by Christie's)
