The Daughter-Heir of Andor is the title given to the heiress-apparent to the Lion Throne of Andor. Although the Andoran Daughter-Heir is generally a princess, she need not be so, as discussed further.
As Andor can legally only be ruled by a woman, the rule over that nation is ideally passed from the ruling queen to her eldest daughter. If the queen has no daughters, the succession to the throne follows to the queen's nearest female blood relation. However, in practice, determining which noblewoman that might be can be very complicated, as the great houses of Andor are heavily interrelated, and many of them all claim a line of descent from Ishara, the first queen and foundress of Andor in the opening stages of the War of the Hundred Years.
In the event of the absence of a clear Daughter-Heir, internal armed struggles may erupt, known outside of Andor as Wars of Succession, and internally inside Andor colloquially referred to simply as the 'Succession' or as blandly as as 'disturbances.'
Prior to the onset of the storyline, Andor had only just emerged from yet another Succession as Morgase Trakand was placed upon the Lion Throne by a coalition of allied houses who successfully completed the claim put forth by Morgase's late mother, Lady Maighdin. Both Maighdin and Morgase were deemed the closest female blood relations to the old queen, Mordrellen Mantear, who had died. Queen Mordrellen's own Daughter-Heir, Lady Tigraine, had gone missing and was declared dead.
It is unknown how legally unassailable the Trakands' dynastic claim was, as it did result in armed conflict requiring a military solution, with numerous allied blocs of houses all contesting the throne. The internal struggles were again repeated when numerous noblewomen asserted a claim as Morgase's Daughter-Heir when both she and Elayne were missing and the Lion Throne was again vacant.
It has become apparent that the claim to the Lion Throne, which may only be ascended to by a woman, can be transmitted through male members of Ishara's line, thus revealing there is no corollary to what is called a Sallic Bar, that is that no claim can be transmitted through a woman. In real world France, no woman could inherit throne in her own right, nor could the male descendant of a king through the female line. For example, the grandson of a French king via his daughter would have no legal claim. As we see in the series, in Andor, numerous powerful Andoran lords are seen trying to assert claims for their daughters and granddaughters.
The Daughter-Heir of Andor is awarded a ceremonial crown, called the Diadem of the Daughter-Heir.