How do titles work for the children of French aristocrats? If the father is a French Marquis does the eldest son have a seperate courtesy title? What about younger children, are they all titled or are they just Monsieur and Mademoiselle?
In the Netherlands, Luxembourg, German-speaking and Scandinavian countries the sons and daughters of a titled nobleman have his titles. The most senior male titleholder is, for an example, THE Count while the others are Count/Countess [name]. In France and Belgium often the daughters do NOT share the titles but have the honorific Demoiselle/Jonkvrouw (= noble lady). It depends on the exact wording of the Letters Patent in which the Nobility has been confirmed.
An example of daughters sharing the title:
The Count de Lannoy (= the actual head)
Count Jehenne de Lannoy
Countess Stéphanie de Lannoy
An example of daughters not sharing the title:
The Count du Parc Locmaria (= the actual head)
Demoiselle Claude du Parc Locmaria
Count Alain du Parc Locmaria
Demoiselle Anne du Parc Locmaria
Count Gaëtan du Parc Locmaria
Another example of daughers not sharing the title
The Prince Ruffo di Calabria (= the actual head)
Don Fabrizio, Prince Ruffo di Calabria
Donna Paola Ruffo di Calabria
Outside the United Kingdom secondary titles are mostly used in Spain. The Heir to the Dukedom of Alba is the Duke of Huéscar, to name an example.