Short answer. No. Article 992 of the Civil Code bars an illegitimate child from inheriting by intestate succession from the legitimate children and relatives of their father or mother. The barrier runs both ways — legitimate relatives also cannot inherit from the illegitimate child. This is a firm legal wall, not a discretionary rule.
What the law says
An illegitimate child has no right to inherit ab intestato from the legitimate children and relatives of his father or mother; nor shall such children or relatives inherit in the same manner from the illegitimate child.
Civil Code, Article 992 — The Barrier Between Legitimate and Illegitimate Relatives. Read the full provision →
The Iron Curtain between legitimate and illegitimate relatives
Article 992 creates what is sometimes called an 'iron curtain' in Philippine succession law. An illegitimate child is cut off from inheriting by intestate succession from the legitimate relatives of his or her parent — including half-siblings who are legitimate children of the same father or mother. The fact that they share one parent does not open the door. The barrier is based on the legitimate or illegitimate status of the deceased, not on the closeness of the relationship.
The rule applies to intestate succession only
Article 992's barrier applies specifically to intestate succession — inheritance without a will. If the legitimate half-brother who died had written a will that left something to the illegitimate sibling, that bequest would be a different matter. Testamentary freedom allows a person to leave property to persons outside the normal line of succession, subject to the legitimes of compulsory heirs. But when someone dies without a will, the intestate rules govern, and Article 992 blocks the illegitimate child's claim entirely.
The barrier runs in both directions
The statute is clear that the restriction is mutual: legitimate children and relatives also cannot inherit by intestate succession from the illegitimate child. If your illegitimate child were to die without a will, the legitimate half-siblings would have no intestate claim on that estate either. The law creates a clean partition: legitimate relatives inherit among themselves through intestate succession, and the illegitimate child's estate passes through a separate line of heirs.
Who does inherit from the legitimate half-sibling?
When the legitimate half-brother died without a will, his estate passes to his own legitimate line of succession — his own legitimate children if any, then his legitimate parents, then other legitimate siblings and relatives in the order the Civil Code prescribes. Your illegitimate child does not enter that succession. The only path to having any share would have been a will — which no longer exists as an option since the half-brother has already died. A lawyer can advise you on whether any other legal avenue is available in your specific situation.