I based the dress off of this one, which is from the 1830's [and her hair is based-off Sarah Josepha Buell Hale's]:
Backstory is she mostly taught Robin & Alfred things their father didn't want them to know (like about their grandfather's culture), giving Robin his nickname (his actual forename is 'Robert'). She died around the time Alfie was 10 years-old. Margaret dislikes that he got his auburn hair from her, and not something similar to her husband's or her's. Roberto dislikes that she married a foreigner, and gave him such a name that he's had to deal with (and changing his surname when his children keep "Cassius" would cause problems too).
Named her "Sophronia".