Did the sisters err in dividing the inheritance equally among themselves to fulfill their father's desire to achieve equality between them in the endowment, after he had singled out one of them with an additional apartment?

A father is legally obligated to treat all his children, male and female, equally. If he favors some of them and dies before rectifying this, the gift must be returned to the inheritance. The agreement of adult, sane heirs to allow a sister to take an apartment in exchange for deducting the difference from her inheritance is permissible.