Prior to his death, H, married to W. with children X. Y. and Z, executed a holographic will entirely written, dated, and signed by him. In his will, H instituted W, X, and Y as bis heirs, and consequently, made testamentary dispositions in their favor. H. however, expressly disinherited Z on the ground that the latter once filed a civil case against him in order to collect a particular sum of money he previously owed Z. (2019 BAR)

(a) Was the disinheritance of Z proper? Explain.
(b) Assuming that the disinheritance of Z was improper, how will it affect the institution of heirs and testamentary dispositions made in II’s will? Explain.