What's suspicious about Rob Altman's sister?

With the continuous updating of the plot of the new Manrob Altman, the "mysterious hand" that initially made everyone question has been determined, and whether the dark Ober will play has also reached a certain clear conclusion. For the appearance of the characters, in addition to the two protagonists, the father and sister who live with them have made many fans question their identity and even the purpose of their appearance because of the plot. Here is a separate question for you. I think what my sister can do is mainly reflected in her usual family and activities. I will give you a detailed explanation of the reasons for saying this.

When Robert Altman's sister first appeared, to be honest, his appearance really gave people a very cordial feeling, and some chubby faces would make the audience feel very cute. In the face of such a pure girl, we really can't associate her with those evil little people. However, in the follow-up plot, some of my sister's performances are really debatable.

First of all, in the third episode, when Rob and his sister went to the scientific research base in Ayran City, Ayran City and Rob's mother had been working together to develop the history of Lingxiang City. Working together for a long time, according to the truth, Ai Rancheng will definitely know that he has a sister, but in the plot, Ai Rancheng shows that he doesn't even know that he has a daughter. Faced with such a plot, it is really suspicious.

In addition, in the sixth episode, the former Lingxiang police often educated Rob and his two brothers when they were young, and he was very worried about living in the sea together. Faced with such a situation, he should also know the existence of his sister, but it is still not reflected in the plot. In addition, during divination, when the fortune teller said there were four people in the family, he obviously gave my sister a close-up. At that time, my sister was very dignified, and the real reason was really doubtful.