Who is Dona Ana from Iberia: Spanish Travels and Reflections and what is their importance?

Dona Ana was one of the illegitimate daughters of Carlos V. She was put away in a nunnery, as all illegitimate daughters were, to make sure that she wouldn't marry and create heirs to the throne that would be unsuitable to rule. She was manipulated by Fray Miguel de los Santos to believe that her cousin, the former King of Portugal, was still alive and that they should wed.