The following are compulsory heirs:
(1) Legitimate children and descendants, with respect to their legitimate parents and ascendants;
(2) In default of the foregoing, legitimate parents and ascendants, with respect to their legitimate children and descendants;
(3) The widow or widower;
(4) Acknowledged natural children, and natural children by legal fiction;
(5) Other illegitimate children referred to in article 287.
Compulsory heirs mentioned in Nos. 3, 4, and 5 are not excluded by those in Nos. 1 and 2; neither do they exclude one another.
In all cases of illegitimate children, their filiation must be duly proved.
The father or mother of illegitimate children of the three classes mentioned, shall inherit from them in the manner and to the extent established by this Code. (807a)