ANSWER:

If he has given all his children equally during his lifetime, without being unjust to any one of them, then this is a gift and it does not come under inheritance. They can keep it for themselves. But if he didn’t actually give it to them and they didn’t possess it but rather, it was a will to be executed after his death, in this case, it must be divided according to sharia.  

My father in his life time gave each son and daughter an apartment.Each of us accepted this gift from him.After he passed away will these apartment will go under inheritance ruling as per sharia or every one can keep their apartment as it is.You have been a great help to me shaykh always.