If he still could not tell that Yun'er's recent abnormality had something to do with his eldest daughter, then he would be too stupid.
Moreover, this elder daughter could still maintain a faint smile when facing her biological mother's nasty attitude. That wasn't possible for an ordinary person, right?
He had watched Yun'er grow up, so he knew best what kind of personality she had. For unimportant people, even if Yun'er would show kindness to them in order to maintain a good image, she would never treat them seriously.
However, even Yun'er was biased towards her so he didn't believe that his elder daughter only relied on Master Nine, who was engaged to her and treated her differently.
It seemed like he could not treat her with the same attitude as before no matter if it was because she still had her memories from when she was young, or because she was not as simple as they thought.