I am currently crafting a feudal system for my world, based off Kings, Dukes, Counts, Barons and Lords. I wanted to create some sort of family tree to create some inheritances and find out what families are currently ruling the Kingdoms, Duchies and Counties.
The question I had was, if a man marries another ruling Family's daughter, can that man inherit the title if no other inheritances are found?
For example: The young Count Advar marries the daughter of Duke Bamblebry. The wedding goes ahead and the daughter and Count Advar live a good marriage. Suddenly, there is a war and Duke Bamblebry and his only living son are killed, leaving only his daughter. Would Count Advar then be able to inherit the Dukedom?