Short answer. No. Article 246 lists the relationships that make a killing parricide, and they are all by blood or by marriage to the offender himself. A stepfather and a parent-in-law are relatives by affinity, not ascendants, so neither falls within the article's list.
What the law says
Any person who shall kill his father, mother, or child, whether legitimate or illegitimate, or any of his ascendants or descendants, or his spouse, shall be guilty of parricide
Revised Penal Code, Article 246 — Parricide: Killing A Relative. Read the full provision →
The article works from a closed list
Article 246 provides that any person who shall kill his father, mother, or child, whether legitimate or illegitimate, or any of his ascendants or descendants, or his spouse, shall be guilty of parricide. Read it as an enumeration, because that is what it is: father, mother, child, ascendants, descendants, spouse. Nothing in the sentence invites extension by analogy to relationships that resemble those. A relationship either appears on the list or it does not, and the ones that do are relationships of blood, together with the single relationship of marriage to the offender.
Why a stepfather and a parent-in-law fall outside it
Both are relatives by affinity — connected to the offender through a marriage rather than by descent from or to him. A stepfather is his mother's husband, not his ascendant; a parent-in-law is his spouse's ascendant, not his own. The article names his ascendants and his spouse, and the possessive is doing work in both places. The one marital relationship the provision reaches is the offender's own spouse. It does not carry through that marriage to the spouse's relatives, and it does not treat a parent by remarriage as a parent.
Outside the article does not mean outside the law
A killing that is not parricide is still a killing, prosecuted under the provisions on homicide or murder according to the circumstances alleged and proved. So the practical significance of the classification is not whether there is criminal liability but which offence is charged, since the elements to be established and the consequences that attach differ between them. Anyone reading this because a charge has been laid should look at the offence actually named in the information rather than at how the incident has been described elsewhere.
Relationship is a matter of proof, not description
Where relationship is what distinguishes one offence from another, it has to be established by evidence like anything else, and the civil registry documents are the ordinary means of doing so. Birth certificates and marriage certificates settle whether a person is an ascendant, a descendant or a spouse; household arrangements and the terms families use for one another do not. If the classification is in dispute in your case, the registry records are where a lawyer will start, so obtain them early.
Related provisions
- Revised Penal Code, Article 246 — Parricide: Killing A Relative
- Revised Penal Code, Article 249 — The Crime Of Homicide