Had to give her some reason to run off.
But then the muse impishly said that this world has the title descend by however it was granted, but they have more variation. There are those that descend by male line. Those that descend by female line. Those that descend by primogeniture regardless of sex but can not go to a sibling. And ultimogeniture, working the same. Perhaps I'll work out a few more exotic ones.
Not that the other significant heir in the story will allow of that. Since he's a distant cousin, and a he, it's got to be a male-line thing.