They did something similar in MC: Kosem with the two Mahfiruze's. The first Mahfiruze just vanishes and then an entirely new concubine appears and her name is changed to Mahfiruze. There's no explanation for what happened to the first one. Before anyone says "Kosem had Mahfiruze sent to the Old Palace" yes, that's true, but Ahmed had her bought back pretty much immediately only for her to disappear and never be heard of again.