Su Xiaofei was aware that it was Housekeeper Chen who let the mother and daughter pair enter their home. The old woman must have been expecting to gain their favors by helping Ye Mingyu claim her spot as the true young miss of the Su family. However, they must be stupid for not knowing that such a title held no importance to Su Xiaofei and it didn't come with wealth and prestige other people thought it had.
So what if Ye Mingyu was the real daughter of Su Haoran? The one who brought money in the family was Yun Qingrong and not Su Haoran. The one who called the shots here was her mother, and obviously Su Xiaofei, since technically, she was legally adopted by her parents and had a say in this household.
Su Xiaofei hid herself next to the wall above the staircase, eavesdropping on the conversation between her mother and their unwanted guests. In the corner of her eye, she spotted Housekeeper Chen in the corner downstairs with an unusual smile on her ugly face.