First of all, thanks to you Agneschen ... I saw the pics you've posted in the Hohenzollern section. It is quite surprising, but I have never seen two of them before.
Linnea,
actually Marie's daughter was called Maria Christina after Queen Marie Christine, Franz II.'s mother. In Theroff's Online Gotha you can find the name "Christina Maria Anna Isabella Natalia Elisa" and in an old biography of Maria Sophia by Clara Tschudi the little girl's name is "Maria Christina Pia Louise".
Maria Sophie lived in Munich after WW I, that's right. I couldn't find any hint that she lived with her sister Mathilde. As far as I know she stayed with her sister-in-law Marie José in the so-called Maxpalais (Ludwigstraße). Some time before her death in 1925, she had a small appartement in the Wittelsbacherpalais.
No one really knows what happend on that November day in 1862. Some sources say that she gave birth to twins - I think this is just a rumour. And there is also no evidence that the baby was given away, probably to his father. Maybe Marie later was in contact to her daughter ... we don't know at all.
We even can't be sure that "Armand de Lavayss" was the child's father. It's bizarr, but a count of this name has never been in Rome. There are hints that Nicolaus of Nassau had an affair with Marie and used "Armand de Lavayss" as a pseudonym.
Marie