Is it permissible to pay for the mother's treatment and illness expenses from the father's inheritance before it is divided among the heirs?

Among the acts of kindness towards a mother is to cover her treatment expenses, even if she is not in need. However, it is not permissible to deduct anyone's share from the inheritors without their permission to pay for the mother's treatment expenses. If she is poor and does not possess the means for treatment, then the cost of her treatment is obligatory upon the wealthy among her inheritors.