Succession
Succession laws in the Empire of Adana are incredibly complex, varying from region to region within the empire, according to cultural customs, the traditions of houses, pacts made before marriages, diplomatic treaties, oaths made, certain imperial laws or those of the empire's constituent realms, political considerations and, every now and then, the prospect of interference by an armed force.
As a baseline expectation, most succession sees a single individual inherit a house's core holdings. However, if a house has a substantial number of holdings, perhaps via conquest or inheritance, these are typically split between multiple successors and the norm is for those who inherited the non-core holdings to establish a new house. The and the generally have this approach, with a common expectation that the eldest child inherits. The has elective inheritance, with all members of a house getting a vote, though the wishes of the former ruler are given very significant regard in these elections, while the parliament selects new monarchs. The has the eldest child inherit and notably has a tradition of keeping a house's holdings intact as a single unit, meaning that it has relatively few but very powerful noble houses. The , with its plutocratic aristocracy, has the eldest child of the head of house succeed as head of house, then determines succession to the rule of each of its constituent city-states by way of a vote in the city councils, which are invariably stacked with the representatives of one of the three largest houses. The rule of Thasen as a whole is determined by its senate.
Adult adoption is occasionally practised among the nobility, notably where inheritance is at stake and a head of house has no children. In such cases, they might adopt a relative, most often one who would inherit due to proximity to the head of house anyway and who is accepted by their house. Adoption which bypasses close family is a sure way to cause unrest among not only one's family but likely also vassals. The adoption of commoners is simply not done. There have been instances of unrelated or common children being taken as wards without being adopted; the nobility don't make much of this provided inheritance is not affected.
Membership of a noble house is only retained for as long as one is not too distantly related to the main line. Once one is far removed from the main line of heads of house, they cease to be noble. The child of a third cousin, for example, is very unlikely to be a member of the house.
What this means when playing the game
Dynastic succession isn't really a core focus of Empire, because it doesn't cover a broad enough timespan. However, it could still be a motivator for characters or a driving force behind a plot. If it is important to you to know further details on how succession for a house might work, you can ask.