When a person interested in the administration of an estate in any court in this state, shall appoint an attorney in fact, resident in the county where the court is held, to represent him therein, and shall cause the letter of appointment to be filed in the office of the clerk of the court in which the estate is administered, where it shall have the same effect as a demand for notice of an order or filing concerning the decedent's estate, all process issued from the court touching the estate may be executed on such attorney, and, when so executed, shall have the same force and effect as if executed on the principal in person.