Patrilineal Descent. Firstly, the office and title are usually passed patrilineally (from father to child) in descending order of male birth then descending order of female birth, hence the oldest surviving son is the heir presumptive. If the heir presumptive produces no heirs, then on the heir presumptive's death the office and title go to the next younger son, etc., then the eldest daughter, etc. The term ‘cadet’ is used to describe family groups that are descendants of younger sons, thus the oldest surviving son of each generation maintains the main or principal family line, and younger sons establish cadet lines. In the case of the chiefly line of Buchanan, the first recognised cadet was Buchanan of Auchneiven and the last was Buchanan of Auchmar. Cadets can have their own cadets, e.g. Buchanans of Drumpellier, Auchintorlie, Craigend and Hillington are cadets of Buchanan of Leny through Gartacharne. When chiefly line is extinguished, the most recent cadet line to branch off the chiefly line becomes the new chiefly line.