As an example, if a person wants all his wealth to be transferred to his wife, and none given to his children (for whatever reason, like the children may be well settled, but the wife may not have any source of income). OR If a person has more affinity towards his one son (again for whatever reason, like this son may have served him well) and would like to give this son a larger share.
If your distribute your wealth during your lifetime, then the laws of inheritance and succession will not apply.
However, a will only takes effects after death. One has no choice in a will. It will have to be distributed in accordance with the Islamic laws of inheritance. This is the command of the Qur’aan. Allah Ta’ala knows better than us who is more deserving of our wealth. (Shaami vol.2 pg.35)
and Allah Ta’ala Knows Best
Ml. Imraan Vawda