Is it permissible for the youngest sister to seize possession of her mother's house if its sale to her is not proven, or should the house be distributed among the heirs according to Islamic Sharia?

It is incumbent upon the daughter to disclose her bank accounts to her mother, and it is forbidden for her to conceal them. Her claim of settling debts will not be accepted without evidence. If the mother conducts a preferential transaction for her daughter by purchasing a house or gifting it to her, this is forbidden unless the rest of the adult, mature heirs agree. Otherwise, the house will be included in the inheritance and divided according to Islamic law. If the mother bought the house and paid part of its price, and then the daughter paid the remainder, the house belongs to the estate, and the amount the daughter paid shall be returned to her. However, if the daughter paid her own money at the time of the contract with the intention of partnership, then she is a partner to the extent of what she paid. The daughter must fear Allah and reveal the truth, and she should know that any preferential gift from the mother must be included in the inheritance and divided among all heirs.