Subject to the provisions of the succeeding articles, the following are obliged to support each other to the whole extent set forth in the preceding article:
(1) The spouses;
(2) Legitimate ascendants and descendants;
(3) Parents and their legitimate children and the legitimate and illegitimate children of the latter;
(4) Parents and their illegitimate children and the legitimate and illegitimate children of the latter; and
(5) Legitimate brothers and sisters, whether of full or half-blood (291a)