Bai Rouyun's identity was special. Although she had been reborn numerous times, and her soul had been shattered, her biggest challenge was that her current soul had not gone through the wheel of reincarnation when it was rebirthed in her current body.
If she had underwent the ordinary path of reincarnation, she would have drunk Grandma Meng's tea of forgetfulness, and would have forgotten all memories of her past life. In that case, even if Bai Mulan had the soul fragment, she would not have any reaction when it came close.
Unfortunately, her soul had not been cleansed and she was now a person with two lives.
She had, in her first life, been born to the Patriarch of the Bai family from the Wushi Continent and his principal wife. Her identity was supposed to be noble but due to the internal strife, she had been tossed to the lower realms as a newborn baby.