In page 9, the Empress says there's a girl, daughter of one of the consorts, who was banished. Could that have been Fon Shen, Mao Mao's mother? From what we know of her back from Ch 37, it's implied she was raised in Hanamachi, and that her "not having a mother" was because of Hanamachi's rules against courtesans being mothers. But it's not stated explicitly, and early on the implication was that she was dead, so we've been misled by "technically true" statements before...
Also, it would kinda fit with Ch 54's ending. "Some people wouldn't be pleased with [Mao Mao being taken as a consort]" could be because she's basically a commoner, or because things would get really messy if someone found out about her lineage...
Furthermore, the novel's author, Hyuuga-sensei, seems to like surprising the readers and setting stuff like this up. For example, Ruo Men being Rakan's uncle, and thus actually a blood relative of Mao Mao's. So it wouldn't be surprising to get something like this.
Or maybe I'm going too far, I don't know.