Archduchess Sophie, mother of Emperors Franz Josef of Austria and Maximilian of Mexico, had only one daughter - Archduchess Maria Anna Karoline (1835-1840). Reportedly, after the death of her daughter, Sophie was inconsolable.
So, while Sophie is still likely to be the ice queen that she was perceived as (that is supposedly a result of the death of the duke of Reichstadt), say Maria Anna's heallth is better and she survives. What does the future hold for FJ's only sister? A prestigious foreign match? Or does she end up like Princess Victoria of Wales, a constant companion to her mother?