I can understand how sending one's daughter away to live with another noble house would discourage one from attacking said house, out of fear for one's daughter's safety. What I don't understand is what would prevent the house into which the daughter married from acting as the aggressor.
While a child produced by the marriage might have a rightful claim to both houses' holdings (assuming, presumably, that the groom was the firstborn son and the bride didn't have an older brother with children of his own), any benefit realized therefrom probably wouldn't be enjoyed by the people actually responsible for arranging the marriage. Did nobles really feel so strong a sense of obligation towards their houses and heirs not yet born as for the possibility of future benefit to the current ruler's descendants to be enough to prevent conflict?
This is a question that I've sometimes wondered about. The benefits for the recipient male-partner's family seem more obvious; they get a dowry, their son gets a (presumably) respectable marriage and they have at least a shot at providing a new generation with the next heirs. Which is where we need to go a little deeper into how it works.
Disclaimer my knowledge is more in Early Modern England in the "Long Sixteenth Century" around 1485-1625 but I have studied the Medieval and broader Renaissance culture too.
Consider firstly, that daughters cost money. You have to provide for them and noble daughters might help a little around the house, but they're too highborn to be labouring maids and too young to manage the household. So past the initial dowry payment its a financial benefit in the long-term to transfer the cost of the lady's living to a husband. Not only does having a husband provide general support and stability, but there is also the dower; an overlooked part of the marriage arrangement where ,in return for the dowry, the husband makes an agreement for what the wife would/will be provided with when widowed to ensure that support continues. Secondly, we need to consider the social aspect. Having your daughter do unmarried was in of itself considered a shameful thing for the daughter and the family. So regardless of exactly how beneficial it was there was a social pressure to do it. With a husband in contrast, a woman would have high status than she did as a daughter especially if the marriage is functional and reproductive.
Thirdly, because the provision of an heir is so important being the one to provide a wife to a first-born son can be a huge bond of gratitude for a major marriage alliance. After that and the dowry there would be social pressure to honour that benefit and be a good ally in return. Fourth, it's worth noting that while women were not able to hold much official power and were discouraged from being "meddling, at the same time men in their lives seem actually to have expected them to work, discreetly, on their behalf. The women were vital parts of maintaining the marital alliance; actively working to bring communication and co-operation between families. We can see in Catherine of Aragon's example how she promoted Trastámara and Hapsburg interests and that she was praised or blamed by her relatives when diplomatic turns occurred. When Robert Cecil's (later 1st Earl of Salisbury) wife Elizabeth Brooke/Cecil died his relationship with her relatives deteriorated not long afterwards, with Henry Brooke, 11th Baron Cobham being arrested in 1603 and George Brooke being executed.
Hope this helps.