All perfect praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon our Prophet Muhammad and upon all of his family and companions.
In principle, there is no room for Ijtihad as regards Sharia matters that are stated whether in the Holy Quran or in the Prophetic Sunnah; accordingly, changing any of which is impermissible.
In this regard, Allah, The Exalted Stated in details the distribution of inheritance in the Holy Quran due to its significance as well clarified in the prophetic Sunnah proven that it is unchangeable at all. Yet, Ijtihad is applicable only pertaining the method of applying the religious ordainment in this regard according to the given issue before Sharia Judge. And Allah Knows Best.