Some months ago I promised to find and post this quote about the practice in the Middle Ages of sometimes changing the given name of a wife. It wasn’t widespread, but it happened often enough to be worth noticing:
“The wife was sometimes so completely absorbed into the family of the one man who had the right to give her children that her own Christian name was changed. (At that time there was no family name or surname handed down from generation to generation.) Mathilde might thus become Blanche or Rose — a mark of her complete break with the past, her completed capture. Yet if she was to play her part in the house and fill it with legitimate children, her blood and her womb were necessary. And in her offspring that which came from her ancestors through her blood would mix with that which her husband inherited through his blood from his ancestors.
“This conjunction was openly proclaimed in the choice of names for the children: boys and girls were named after forebears from both the father’s and the mother’s side. A family might appropriate a wife by changing her name, yet outsiders might still invade the clan in the form of the descendants named after them.”
Georges Duby, The Knight, the Lady and the Priest: The Making of Modern Marriage in Medieval France (1983), 44-45.