Slaughtering the Ud-hiyah on behalf of a deceased person who made no will of this

Q 3: My paternal grandmother passed away and left some sheep. Since she passed away, my father offers an Ud-hiyah (sacrificial animal offered by non-pilgrims) on her behalf every year without any will from her. What is the ruling on this action? Does the Ud-hiyah have a specific time before or after my father's Ud-hiyah? Benefit us with your answer! May Allah reward you with the best! (Part No. 10; Page No. 442

A 3: If the Ud-hiyah on behalf of your father's mother was according to her will, what she willed has to be fulfilled. If it is a donation from your father to be taken from his mother's wealth which she left behind, the agreement of all the inheritors has to be given.If a Muslim wants to offer an Ud-hiyah on behalf of himself and another one on behalf of another person, he is to begin with his own Ud-hiyah. The Ud-hiyah on behalf of the deceased is Mashru` (Islamically permissible), whether it was offered according to a will or not because it is a type of Sadaqah (voluntary charity).May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.