Infanta D.Isabel Maria was her father (D.João VI) favourite daughter.
After the wedding of her elder sisters, Infantas D.Maria Teresa, D.Maria Isabel and D.Maria Francisca, she was her father's great support and comfort in the dwelling times that arouse after the RF returned from Brazil .
As you may know, the king, who is usually depicted as an irresolute and even an imbecile, was in fact one of the most able kings and he had the vision to antecipate what might happen when Napoleon would invade Portugal - he would share the fate of his spanish cousins.
D.João was a perfect constitutional king and that infuriated his wife D.Carlota Joaquina who plotted against him with all her means, throwing her son D.Miguel against the king.
On one occasion, things became so difficult that, after a ball at the french embassy, attended by the king and the Infanta, the ambassadors of France, Spain and Britain managed to transfer them to a british vessel staying in the Tagus river to prevent them from being captured by D.Miguel's followers.
From there, the king was able to dismiss D.Miguel from his military post and secure that constitutionalism would prevail.
At the vessel however, the Infanta met an english officer who seduced her and she became pregnant.
That was really unfortunate for her as, at the time, there were talks to her marriage to the Prince de Condé, who broke the marriage as he heard of the pregnancy.
Opposite to what Yseult wrote, a girl was born and was raised near the palace . ( Some authors claim she had another child.)
On Eduardo Nobre's "Paixões Reais" there is a passage that confirms that not only she survived as she was (distantly) acknowledged by the RF.
One day, her cousin Queen D.Maria II had gone for a ride on a carriage and at the sidewalk there was D.Isabel Maria's daughter.
The Queen waved at her so much that she lost her bracelet. The girl caught it and was returned it to the queen that offered it to her.
D.Isabel Maria was a neurotic woman. She was very religious and in her will, she left all her wealth to some religious order.
I will try to find my "Eduardo Nobre" as I am writing from memory.
