Under Aaron their father— The high-priest is here called by the general name of Aaron, as being his successor. The meaning is, "under the inspection of the high-priest."
Related Commentaries of 1 Chronicles 24:19
1 Chronicles 24:19
19 These were the orderings of them in their service to come into the house of the LORD, according to their manner, under Aaron their father, as the LORD God of Israel had commanded him.