The rumors that Ming Shu was Master Liu's illegitimate daughter spread after the light festival. It was said that Master Liu provoked some woman outside and because he was afraid that his wife would find him for trouble, he didn't dare to bring the woman home.
After that, the woman gave birth to a daughter and Master Liu brought her to the Liu residence with the story that he picked her up.
Ming Shu knew what they were trying to do.
However, she heard that Liu Xinyue got sick after she came back from the light festival. She hadn't recovered yet and her wedding date was getting nearer.
But, the imperial decree from the palace hadn't come yet.
Liu Xinyue could only control the rumors now. After a while, everyone would know that Ming Shu was an illegitimate daughter.
Coincidently, when Liu Xinyue was born, Lady Liu went back to her parents' home to rest because she was not in good health. Liu Xinyue was brought back after she was born.