As for why she was not made Empress, it was simply because the Emperor had once promised the late Empress Chunyuan that the position of Empress must always belong to a woman of the Ulamara clan.
Although the Empress had been cast into the Cold Palace, her title was never stripped from her. This was the Emperor's way of fulfilling his promise to the late Empress Chunyuan.
On the day Yu Ying'er held her grand ceremony as Imperial Noble Consort, many imperial relatives and nobles came to the palace.
Chapter 268