Any dynasty member over the age of 17 may be married to a member of another dynasty. Ensuring that your younger dynasty members are married in this way has key benefits. Not only can you gain Status from such a marriage, but also any Feud Score existing between your two Houses will immediately be reduced. Additionally the married couple will have the chance to swell the ranks of your dynasty by producing children, thereby ensuring the continuation of your House line.
Be warned, however, that marrying 'below your station' will result in a loss of status for your House, rather than a gain - so choose your partners carefully.
There is a monthly chance that any married couple will produce children. This chance decreases with the age of the female partner, and also decreases if the prospective mother is in education, heading a sphere, or acting as senator for a planet - since these activities require a significant commitment in themselves.
The lineage of your House and the House of the other party in the marriage will determine whether the children of this marriage will join your House or the other House in the union. If both Houses are patrilineal, then both the newly-married wife and the children of the marriage will join the House of the husband. If both Houses are matrilineal, this situation is reversed. If the Houses are of mixed lineage determinations, then male children will join the patrilineal House and female children the matrilineal. In this case, both parties in the marriage will remain members of their original dynasties and can continue their duties if running any spheres of activity.
When you make a marriage proposal, you will see on the screen exactly what will happen to the children of that marriage.
On your dynasty screen, you will see a link 'Eligible to Marry' alongside the members of your dynasty to whom this applies. Clicking the link will take you to a search criteria screen, where you may filter the eligible candidates according to status, attributes, or other criteria. Once you submit this search, you'll be presented with a list of eligible candidates from other Houses, and you may choose to issue proposals to any or all of them.
There are several factors to a given proposal. Firstly, a dowry may be either paid to or received from the other House. If, for example, the other House is much higher in status than you, they may lose status through the marriage, and a dowry paid to them is one way of sweetening this loss. Note that if the party concerned cannot afford the dowry at the time of the marriage, then it will be called off and both Houses will lose status.
In addition to the dowry, the cost and size of the ceremony must be determined. This will affect the status gains from the marriage - a more expensive ceremony will increase the amount of status gained, as one might expect. The cost shown is for each House, and is therefore half the actual total cost of the ceremony and associated festivities.
Once you have decided these amounts, you can submit the proposal and the other House will receive a message informing them that a proposal has been made. If the proposal is rejected, you will lose one status. If a proposal is ignored, it will be forgotten about after a few months, with no status loss - letting you down gently, if you like.
You can view all your outstanding proposals (both sent and received) via the link from the dynasty screen. You may withdraw proposals made at any time, with no status loss.
As soon as the subject of a proposal accepts the proposal, the marriage ceremony costs are deducted and the ceremony scheduled for one months time from the date of acceptance. Either party can pull out during this time, but the ceremony costs will not be refunded and both parties will lose status if this happens. Any dowry due is not paid until the time of the ceremony itself, after which the couple are wed and the union between your two Houses is complete.
It is important to realise that when a marital partner joins your House as a result of a marriage, that character will not be considered suitable for any head of sphere role. The new family member is not yet trusted or held in high enough esteem to do so. Any offspring of the marriage, however, will not suffer from such a stigma.
You can view your existing marriages by following the link from the 'Marriage Proposals' screen, which in turn is accessed via your 'Dynasty' screen. From this screen it is possible to annul an existing marriage, should you wish to do this for whatever reason. However, both Houses concerned will lose 5% of their status immediately upon the annulment of the marriage, as a result of the scandal that this entails. Additionally, the House to which the other character belongs will receive increased feud score against your House.
Annulling a marriage under which your character has joined another dynasty, will return the character to your own dynasty. Note however that if the other player leaves the game, your former dynasty member is gone forever, deleted along with the departing player's other dynasty members.
As seen in the Rulebook
The most desired weddings are those that marry a Matriarchy and a Patriarchy together. In this case, both Houses keep their dynasty members, and each house has a 50% chance of keeping each child that is sired. In cases where 2 patriarchal houses or 2 matriarchal houses wed, one house will usually be getting the very short end of the stick. There are reasons for doing this - sometimes a house may pay a rather large dowry in exchange for an advantageous wedding arrangement. In many cases, the paying house is a much larger status, so the house losing a dynasty member may also be gaining considerable temporary status.
Houses with dynasty members that follow a faith may also choose to marry these relatives away so that other houses can choose their religion as a House religion.