Here the author speaks of Absalom urging David to let Amnon come as if he were putting physical pressure on him. Alternate translation: "Absalom begged David for Amnon to come" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This does not include Absalom and Amnon who is dead. It includes the rest of the sons that the king allowed to go to the celebration. Alternate translation: "the rest of the king's sons" (See: [[rc://en/ta/man/translate/figs-synecdoche]])