In default of parents or a judicially appointed guardian, the following person shall exercise substitute parental authority over the child in the order indicated:
(1) The surviving grandparent, as provided in Art. 214;
(2) The oldest brother or sister, over twenty-one years of age, unless unfit or disqualified; and
(3) The child's actual custodian, over twenty-one years of age, unless unfit or disqualified.
Whenever the appointment or a judicial guardian over the property of the child becomes necessary, the same order of preference shall be observed. (349a, 351a, 354a)