The Baroness was known for "educating" young women--sort of a private finishing school--in her home in the Leopoldstadt. In the following months, after Mozart's then fiancé, Constanze Weber, quarreled with her mother, Mozart took her to the Baroness' to live for several weeks. Then, in August of 1782, when Mozart and Constanze were married, it was the Baroness who hosted their wedding dinner in her home. It was also the Baroness to whom Mozart wrote of a lovely red coat that would go elegantly with some fine mother of pearl buttons with gold stones.
"I really must have a coat like that, as it's worth it just for the buttons that I've been hankering after for some time ... They're mother-of-pearl with some white stones around the edge and a beautiful yellow stone in the centre."The Baroness had the coat made as a gift for Mozart.
Mozart wrote to his father, Leopold, of the Baroness Waldstätten, and in the spring of 1785, when Leopold visited his son and Constanze, in Vienna, he met the Baroness and grew quite fond of her.
In So Faithful a Heart we see Nancy, Mozart, and the tenor, Michael Kelly with the Baroness at her husband's estate in Klosterneuburg, where it would not have been out of the ordinary for her to have stayed when her husband was away.