Y) Yes. When there is linear ascendant
Heirs are linear ascendant only.
As for the article, Article 889 of the Civil Code set out ((Right of Inheritance of Lineal Ascendant and Sibling)
(1) In the the case where there is no person to become an heir pursuant to the provisions of Article 887, the following persons shall become heirs in accordance with the following order of rank:
(i) lineal ascendants of the decedent; provided that between persons of differing degree of kinship, the person who is of closer relationship shall have higher priority of inheritance;
(ii) siblings of the decedent.
(2) The provisions of paragraph (2) of Article 887 shall apply mutatis mutandis to the case referred to in item (ii) of the preceding paragraph.
The statutory inheritance is shared equally by linear ascendant.