Esther 2 says:
¹²In the twelve months before her turn to go to King Xerxes, the harem regulation required each young woman to receive beauty treatments with oil of myrrh for six months, and then with perfumes and cosmetics for another six months. ¹³When the young woman would go to the king, she was given whatever she requested to take with her from the harem to the king’s palace. ¹⁴She would go there in the evening, and in the morning she would return to a second harem under the care of Shaashgaz, the king’s eunuch in charge of the concubines. She would not return to the king unless he was delighted in her and summoned her by name.
Does a woman officially become a concubine of the king after spending a night with the king? Was the second harem just temporary housing?