The child could have been named as the executor while a minor and still a minor when the father died, and if so, the minor would have had to get a person of 21 or older to assist him/her in carrying out the duties of an executor. A minor could not carry out the duties of an executor alone. The age of majority during this period was 21. If you see the son getting the Letters of Administration and carrying out the Inventory and Appraisements, etc., then you know he is at least 21.