Most importantly, Jian Ai had never treated Jian Changsheng as her father. There was no need to mention it when she didn't know in the past. Even if she knew now, she didn't think too much about their new relationship.
To her, Jian Changsheng was just the CEO of the Jian Group. If she had to admit that they were related, it would only be a competitive relationship.
Therefore, Jian Ai didn't care who Jian Changsheng's son was. She was willing to be close to Jian Yichen because of Jian Yichen himself. It had nothing to do with anyone else.
Otherwise, she wouldn't have to think about Jian Changsheng. Just thinking about Jian Yiyi gave her a reason to hate Jian Yichen, but Jian Ai wouldn't do that.