" Once she gets married to Fourth Lai, she can make a fuss every time. She can come to the Yamen and say that she was beaten up by Fourth Lai and send him to prison."
" She can also threaten Old Madam Lai by telling her that she knew that the Lai family was scheming against me, though Old Madam Lai will be confused about where she got to hear it, just say that she heard it in the temple itself."
" After that, your sister will silently listen to that woman and indirectly to your orders. I am not a commoner and I have the backing of the Emperor as you can already see, just let it slip that I have a prince living with me at the house and you will see how well your sister will cover her mouth."
The reason Su Wan did not want to get involved with this matter was that she did not see the need to dirty her hands. She would rather stir sh*t rather than getting involved in sh*tty matters.