Hostages
If a clan continually rejects your diplomatic offers you can barter with the life of a hostage as the bargaining chip. A hostage is a randomly chosen member of that clan's family, older than five years of age but never a general. Once taken as a hostage no action can be performed on or by the character until they are released. Hostage-taking has a time restriction on it of eight turns, and if the deal has been upheld up to that point the character is returned alive and the diplomatic agreement between your two clans continues. If the agreement is broken during that time the hostage is killed. A hostage can only be included as part of a deal, never as a deal in itself.