Short answer. Yes. The Civil Code expressly allows this. A single person may be named as substitute for two or more heirs in a will. This is called a brief or compendious substitution — the same substitute steps in for each of the designated heirs if any of them cannot or will not inherit.
What the law says
one person for two or more heirs
Civil Code, Article 860 — Brief or Compendious Substitution. Read the full provision →
Brief substitution: one substitute, several heirs
Article 860 of the Civil Code provides two variations of what is called brief or compendious substitution. The first is that two or more persons may be named as substitute for a single heir. The second — which directly addresses your question — is that one person for two or more heirs is equally valid. A testator who names a single cousin as substitute for both of his children, for example, is doing something the Civil Code explicitly permits. The will does not need to name a separate substitute for each heir.
What triggers the substitution
A substitute heir steps into the picture when the primary heir cannot inherit — most commonly because the primary heir predeceased the testator, refused the inheritance, or was disqualified from inheriting. If your father named a single substitute for two of his heirs, the substitution activates separately for each of them. If one primary heir dies before the testator but the other accepts the inheritance normally, the substitute takes the share of the heir who could not inherit, while the other primary heir keeps their own share. The substitute fills the gap, but only where a gap actually opens.
The substitute takes each heir's portion
When one substitute is named for multiple heirs, the question arises of how much they receive if more than one primary heir cannot inherit. In general, the substitute takes whatever each primary heir would have received. If both primary heirs could not inherit, the single substitute would take both shares — unless the will specifies otherwise. The testator may of course include conditions or restrictions on how much the substitute receives, but absent such instructions, the substitute steps into the full position of whichever primary heir they replace.
Practical considerations for will drafting
Naming one person as substitute for multiple heirs simplifies the will and reduces the risk of a gap if several primary heirs predecease the testator or refuse their inheritance. It is particularly useful in family situations where the testator has several children and wants one trusted person — a sibling, a grandchild, a close relative — to catch all the shares that go unclaimed. The will should make clear who the primary heirs are, who the single substitute is, and under what circumstances the substitution takes effect, to avoid ambiguity during the settlement of the estate.