I currently do not understand the princess. does she have two souls in one body or is it just lady Gu's soul with…
So it's not exactly that GQ became the princess. Their souls actually merged into one body. GQ is still the one in control—it's her consciousness that's making all the decisions. The princess's memories just overlap with hers, so she has access to everything SXH experienced without becoming a completely different person.
When Shen Ying Ruo talks to the second prince, she says her mother died in prison? Wasn't her mom just thrown…
I think the ledger was mainly used to expose Prince Kang's corruption, and his sister was implicated in it as well. If you look closely at the scene where they're announcing Prince Kang's crimes, the woman who hangs herself in prison is actually Kang's sister. That's why later SYR says that her mother died in prison. So it wasn't just Prince Kang who fell because of the ledger—his entire family was dragged into the case, and his sister ended up lossing her own life in prison.
1 
i can't beleive he was in FOF
he got a glow up
XIEXIE
XHY buddy why not you show your face !!! to her like
"it's me hii,
I'm the one helping you ,its me"
If you look closely at the scene where they're announcing Prince Kang's crimes, the woman who hangs herself in prison is actually Kang's sister. That's why later SYR says that her mother died in prison.
So it wasn't just Prince Kang who fell because of the ledger—his entire family was dragged into the case, and his sister ended up lossing her own life in prison.