Short answer. The rest of the will remains valid. Article 841 is explicit: a will does not fail simply because the named heir is incapacitated to succeed. All other testamentary dispositions in the will must still be carried out, and whatever the incapacitated heir cannot take passes to the legal heirs.
What the law says
A will shall be valid even though it should not contain an institution of an heir, or such institution should not comprise the entire estate, and even though the person so instituted should not accept the inheritance or should be incapacitated to succeed. In such cases the testamentary dispositions made in accordance with law shall be complied with and the remainder of the estate shall pass to the legal heirs.
Civil Code, Article 841 — A Will Is Valid Even Without an Institution. Read the full provision →
The will is not invalidated by an heir's incapacity
Philippine law treats the validity of a will separately from the ability of a specific person to receive under it. Article 841 lists several scenarios that do not invalidate a will: the complete absence of an heir institution, an institution that covers only part of the estate, the named heir's refusal to accept, and the named heir's incapacity to succeed. In every one of these cases, the will stands. The failure of a single institution does not bring down the entire testamentary document.
What happens to the share the incapacitated heir cannot receive
When the named heir is incapacitated, that person's share does not simply vanish into the estate for the other beneficiaries to divide. Article 841 says the remainder of the estate — the portion not disposed of by effective testamentary dispositions — passes to the legal heirs. Who those legal heirs are depends on the decedent's family situation and the rules of intestate succession. The incapacitated heir's portion follows the line of intestate succession as if that portion had not been covered by the will.
Other dispositions in the will continue to operate
The rest of what your father wanted — legacies to specific people, conditions attached to gifts, instructions about how property is to be used — all of those testamentary dispositions made in accordance with law must still be carried out. The will is not read as a single package that collapses when one part fails. Each valid disposition stands on its own, and the incapacity of one beneficiary does not infect the parts of the will that concern other beneficiaries or other assets.
Implications for the estate settlement process
If you are managing your father's estate and one of the named heirs is legally incapacitated, the estate settlement must still proceed. All valid bequests and legacies in the will should be honored. The portion the incapacitated heir cannot receive is identified and treated as passing by intestate succession among the legal heirs. This may require some analysis of the exact wording of the will to determine whether accretion applies — whether another beneficiary in the will absorbs the lapsed share — or whether the intestate rules govern. A lawyer can help map out who receives what given the specific facts of your father's estate.