Interpretation of residury Gift

I have a standard form precedent DIY homemade Will leaving the residue of an estate to “X Y & Z” There is standard form wording as to substitution if any of them dies before the Testator but this has not been completed as to name beneficiaries.

Y has died and I understand that since there are no words indicating severance then I should treat Y’s interest as passing to X & Z who survived our deceased. Do forum members agree with me?

Jensen Bourke
Bennett Oakley