The engagement of Maria Annunziata and Duke Siegfried in Bavaria was in 1902. They spent a lot of time together during their childhood, because Siegfried and his younger brothers had a very close relationship to their uncle Duke Carl Theodor and his wife Marie José. Marie Therese, Maria Annunziata's mother, was Marie José's sister and visited Tegernsee and Possenhofen very often with her daughters.
After the engagement, Siegfried accompanied Miana, her sister Elisabeth (Liesl) and Archduchess Maria Theresia on a journey to England. In this time, Siegfried became strange. After they had returned to Vienna, Miana asked her uncle Emperor Franz Joseph for permission to break off.
Siegfried took part in horse racings. In 1899 he fell off a horse and was hurt badly. Marie Redwitz, a lady in waiting of Carl Theodor's daughters, wrote that this was the cause of his strange behaviour. In 1908 he was incapacitated and brought to a mental home in Nuefriedenheim. But later he was able to live in his house in Schwabing. He died unmarried on 12th March 1952 - two days after his 76. birthday.