There is really nothing in the way of you selecting an executor to your estate in the event of your death as long as they are not minors and are in good moral character, meaning they are not in any way criminal in simpler terms. In case you select a minor to execute your estate, they are to be managed by either a lawyer you designate or another alternate executor till they reach legal age upon which the rights reverts to them without question. They can have certain rights such as administer your estate till the minor comes of age enough to make decisions on their own.