"your (formal plural)" in French

“Vos” agrees in number with the noun that follows, not with the number of people we’re talking to. It is the same in both masculine and feminine forms.

e.g:

Marie asks Michel and Jeanne : “What’s the name of your children?” (Comment s’appellent vos enfants ?) because children (enfants) is a plural word.

Michel and Jeanne reply: “Our children are called Tom, Jerry, Léa and Alice.” (Nos enfants s’appellent Tom, Jerry, Léa et Alice.)