"Money moves mountains, they say. Regrettably, unless both of you know a noble who can help go against the Blackheart family, I don't think you will be able to live a peaceful life in Lusterfall City for a long time. You might better pack your things and leave in less than a day of entering the city."
"I know it sounds drastic or crazy, but you have to remember one thing. Everyone gets to live only once. Thus it's better to choose a happy life instead of a regretful one."
"Deciding to leave it to fate and see how it goes or pack your thing in a hurry and go. You are the one who has to decide since it's your life." Vincent ended his suggestion.
[I agree with your thinking. Furthermore, Demel Blackheart would discover how something went wrong with his disgusting plan to make money. Telling these girls to leave by mentioning a possible future is the best way to go for both them and us.]