(Y) Yes. The deceased has the child.
A child and a spouse are heirs.
The legal inheritance is one-half of the spouse and the one-half is devided in proportion to the number of children. If you have a child but have passed away, your grandchild will succeed the child.
Article 900(Statutory Share in Inheritance)
Article 900 If there are two or more heirs of the same rank, their shares in inheritance shall be determined by the following items:(i) if a child and a spouse are heirs, the child‘s share in inheritance and the spouse’s share in inheritance shall be one half each;
The article is Article 887 of the Civil Code (Right to Inheritance of Child and Heir per Stirpes, etc.)
(1) The child of a decedent shall be an heir.(2) If a decedent‘s child has died before the commencement of inheritance, or has lost the right to inheritance by application of the provisions of Article 891 or disinheritance, the child of the decedent‘s child shall be an heir as an heir per stirpes; provided that this shall not apply if the child is not a lineal descendant of the decedent.(3) The provision of the preceding paragraph shall apply mutatis mutandis to the case where an heir per stirpes has died before the commencement of inheritance, or has lost the right of inheritance as an heir per stirpes by application of the provisions of Article 891, or by disinheritance.
Inheritance between legitimate children and non-legitimate children has been different in the past, but is equal (Article 900 of the Civil Code).