“King David assembled at Jerusalem all the officials of Israel, the officials of the tribes, the officers of the divisions that served the king, the commanders of thousands, the commanders of hundreds, the stewards of all the property and cattle of the king and his sons, together with the palace officials, the mighty men, and all the seasoned warriors.”
King David gathered together his close friends, that is to say anyone with any authority. He had all the officials of Israel and the various tribes. He had officers of all the army and his warriors. He also had all the stewards of this property and all the palace officials. There was no mention of this in 2 Samuel, but this author wants to glorify the power and wisdom of King David.