How can a property consisting of a shop, a warehouse, an office, and 4 residential apartments be divided among three sons and three daughters, given existing rental contracts for some of the children, in a way that ensures fairness and avoids future disputes, either through a will or immediate distribution?

You must establish ownership of your wealth to avoid claims from your children after your death. You do not need a will for how it should be divided, as each heir receives their rightful share according to Islamic law.

As for dividing the inheritance before death, it is permissible as a gift (hiba) provided it fulfills the necessary Islamic conditions. However, it is not valid as an inheritance, because a living person cannot be inherited from. Such a division would be void if it is not through a lawful transfer of ownership.