مسائل المنتخبه (Articles Of Islamic Acts) - الخوئي، السيد أبوالقاسم - الصفحة ٥٧٨ - ORDERS REGARDING WILL (WASIYYAT)

executor takes notice of the fact (of his appointment as executor) when due to serious illness or some other obstacle the testator cannot make a Will to some other person, he should, on the basis of precaution, accept the Will.
٢٧٢٣. If a person who has made a Will dies the executor cannot appoint another person for the performance of the tasks as bid down in the Will of the deceased, andkeep aloof himself. How ever. if he knows that the deceased did not mean that the executor should perform the task himself and what he wanted as only that the task should beaccomplished, he may appoint another person as his representative.
٢٧٢٤. If a person appoints two persons as executors jointly and if one of them dies or becomes insane or apostatizes, the Religious Head can appoint another personin his place and if both of them die or become insane or apostatize, the Religious Head can appoint two persons in their place. However, if one person can execute the Will itis not necessary to appoint two persons for the purpose.
٢٧٢٥. If an executor cannot perform the tasks as laid down in the Will of the deceased alone, the Religious Head can appoint other person to assist him.
٢٧٢٦. If a portion of the property of a dead person perishes while in the custody of the executor, and if he has been negligent in looking after it, or has handled it wrongly for example, ii the dead person has willed him to give such and such quantity to the indigent persons of such and such city, but he has taken it to some other city and it has perished on the way, he is responsible for it. In case, however, he has not been negligent and has not handled the property wrongly, he is not responsible for the loss.
٢٧٢٧. If a person appoints someone as his executor and says that it he dies such and such person should be executor in his place the second executor should perform the tasks laid down