Is it permissible for three sisters to make a notional sale of their shares in a house to each other to prevent the heirs from selling it after the death of one of them, knowing that the house will return to the heirs after the death of the last of them, and does this act violate Islamic law and incur Allah's wrath?

What you have done by way of contract is not a real sale, because it does not involve transferring ownership to the buyer. Rather, it is a circumvention to seize the rights of the heirs, and this is not permissible in Sharia (definition), due to the saying of Al-Nawawi: "Sale is the exchange of money for money or its equivalent by way of transfer of ownership," and due to the saying of Ibn Hajar Al-Haytami in Al-Fatawa Al-Kubra: "And if that was by way of division among them without a legitimate transfer of ownership, then that division is void. So, if he dies, all that he owns is an inheritance for his children." The forgiveness of the brothers does not make that permissible. What is obligatory upon you is to cancel these contracts, and your brothers have the right to waive their share of the house to you.