Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
According to the law of al-wasiyyah al-wajibah (binding will), you, your two brothers and your sister are entitled to inherit from whatever your grandmother has left just as your father would have had he been alive. This share does not exceed one third of the estate.
Answering your question, Dar Al-Ifta Al-Misriyyah, states:
Based on the law of al-wasiyyah al-wajibah (binding will), you are entitled to inherit just as your father would have had he been alive.
Al-wasiyyah al-wajibah refers to the right of children to inherit the share of a predeceased parent in the estate of a deceased grandparent. This share does not exceed one third of the estate.
Al-wasiyyah al-wajibah applies if you live in a country that implements this law.
Almighty Allah knows best.
Source: Dar Al-Ifta Al-Misriyyah