Is it permissible to register the apartment, the car, and the retirement bonus in the name of the daughters, especially the one with intellectual disability? And would that be considered a sin, given that there is a will stipulating the distribution of entitlements according to Sharia?

A man writing over his property to his daughters and wife can be either a will, or a gift during his lifetime.

If the intention is to transfer ownership to them after his death, then this is a will benefiting an heir, which is not valid according to the Prophet, peace and blessings be upon him, who said: "Indeed, Allah has given every rightful person his due; therefore, there is no will for an heir," unless the heirs consent.

However, if it is a gift during his lifetime, meaning they take possession of it and dispose of it, then this is a permissible gift. But, it is obligatory to treat all children equally in such a gift. It is permissible to favor a sick daughter due to her illness. Furthermore, many scholars hold that it is not valid for a man to gift his residential home to his wife, and some stipulate that the house must be free of belongings not belonging to the wife who is receiving the gift. It is forbidden to intend to disinherit some heirs.