the.com/line of succession

means The official order in which people would inherit a throne, title, or position if the person currently holding it died or stepped down.

from A straightforward compound: 'line' in the sense of a lineage or genealogical chain, from Latin 'linea' (a string, a line), and 'succession,' from Latin 'succedere' — to come after, to follow up, literally to go up under or close behind. The phrase itself emerged in English as monarchies formalized inheritance rules, turning the chaotic business of who-gets-the-crown into an orderly numbered list — so that even grief could have a queue.