Is it permissible for two wives to uncover their faces in front of each other if they are married sisters living in the same apartment, knowing that they are righteous?

A woman must veil herself from non-mahrams, such as her husband's brother. It is not permissible for her to uncover herself before her husband's brother or to be in seclusion with him. A man must not leave his wife with his brother in the house if he goes out, for the Prophet, peace and blessings be upon him, said: "No man should seclude himself with a woman," and "Beware of entering upon women," and especially "the brother-in-law is death." To avoid temptation and adultery, the house can be divided into two independent sections, and the door to the section designated for the wife should be locked with a key that the husband carries when he goes out. If the brother becomes angry, then let him be angry, because this measure is to protect everyone from the whispers of Satan. Also, uncovering the face before the husband's brother is forbidden, because he is a non-mahram to her.