The thing is, Maomao is absolutely of the correct sort of lineage to marry into the royal family. Lakan is one of the Emperor’s most trusted advisors and the head of an important family; he’s on par with Shishou, whose daughter is one of the Emperor’s highest ranking concubines. Maomao may have been born a bastard, but her parents are married now and Lakan considers her a daughter, which (to my understanding) would have been enough at the time to retroactively make her a legitimate child. If she were to wear her lineage openly, she would be of higher standing than almost everyone she interacts with.
Shishou/his clan is a governor of the Northern Territories and Prime Minister while Lakan is the head of what appears to be a merchant clan but I’m not sure how much difference in rank that actually implies in pseudo-Ming China. In concrete terms their power and influence isn’t comparable. Either way, it’s not like they’re obsessed with historical accuracy and if they wanted they could pick the option with the most drama.
That said, in a later second season episode Jinshi literally says this exact train of logic so the gates are open and it’s just a matter of him deciding she’s worth the drama and becoming a perceived rival to his brother again.
In this way the law of drama works in their favor and therefore the ship shall sail (presumably after the plotline with a viable rival for Maomao’s affections)
Jinshi-sama, the series has no romance tag, it can’t happen.
What kind of fighting style does a birth master use?
BJJ (Birthing Jiu-Jitsu)