About the inheritance in the Quran

Some rich people in the West when they die, they bequeath their wealth to their dog, or to one of their family and deprive the other family members of their rights in the inheritance.

I know that a Christian in Iraq who was rich, he bequeathed his wealth to one of his daughters and deprived all the rest of his seven sons and daughters.

So do you know about the law of inheritance in the Quran: how marvelous!

God assigned to every one of the near relatives of the dead a certain share of the inheritance: not all of them are equal: the son, the daughter, the grandfather, the grandmother, the grandson, the granddaughter ..etc.

According to a system of dividing the wealth in justice: the justice is not to give the brother the same as his sister: the son has many responsibilities more than his sister has.

So how can you object, while your system is defective?

If a man dies, like a rich man from Texas, can anyone of his sons or daughters or his father or mother if they are living: can anyone of these guaranty how much this man will give to them out of the inheritance?

Will the wife take all the wealth of the deceased man, or will the husband take all the wealth of the deceased wife? And what share is guaranteed for his sons and daughters.

And if the man who has died wrote a bequest or a will to give all the inheritance to his friend, can anyone of his family object?