I smell a big con here and I'm curious who is pulling this off...

How could a lowly prostitute feel comfortable blackmailing the daughter of powerful Mr. Paik and comfortable enough to not worry about her head being chopped off?

I'm wondering how a man so sweet and nice and lovely as Jin's father ended up with such a mean, nasty, money-hungry prostitute as Jin's mother. Aww at Jin being raised by his father. I think his father is such a wonderful man. How terrible that Jin would face shame for having such a wonderful, caring father, simply because he is a fisherman.

I think Jin's mother is so hungry for money that she would risk anything to get her hands on 100,000 bucks...even her life. I didn't find anything weird about what she was doing. Disgusting yes, a con? nah

I dont think it was a con necessarily, just the fact that she wanted the money. I accept that part of the plot at face-value, but you never know with this show.