Is it permissible to change the inherited family name, which varies in its formulation among family members, to a unified name, in order to unify the lineage, despite the opposition of some family members?

The basic principle is that changing names is permissible unless it leads to attributing a person to other than their father. If a person changes their name and is attributed to other than their father, they have committed a grave sin, and upon them is the curse of Allah, the angels, and all people. The Prophet, peace and blessings be upon him, said: "Indeed, among the greatest slanders is for a man to claim a lineage other than his father's," and "Do not disown your fathers, for whoever disowns his father has committed an act of disbelief." Therefore, one must adhere to the name by which the family is known.