This can be stated as an indirect quotation. Alternate translation: "have you said that Adonijah will reign after you, and he will sit on your throne?" (See: [[rc://en/ta/man/translate/figs-quotations]])
Sitting on the throne is a metonym for being king. See how you translated this in [1 Kings 1:13](./13.md). Alternate translation: "he will be king just as I was"