After reading some of the comments here, I realized Bella and Jolina might actually be the bitches that's gonna screw everyone over.
I went and played some scenes from the game again:
Hacked PC scene with Bella's and Jolina's pic showing up
Carnival fortune teller scene where the prediction of a snake, especially a snake that is coiling, mentioning of the sisters, introduced to a blonde who's a lesbian, coiling snake will visit soon
The lawyer scene at the end just pretty much sums it up where he mentions the woman knows everything, is cold and deceitful, is relying on MC's task or decision, and a home is a castle
Main take away I got from that is that Bella is the only other person at the time that knew the father, has been living in the same house as Elaine whom had her requirements of the will on her PC which used to have no password, is in contact with MC, and Dizzy can be like Izzy for Isabella or Belle.
Especially after the lawyer scene at the end of Ep 19 did it make sense. The person that arrives at the beach house was Belle, who tended to be VERY clingy and literally wrapping around the MC, like a coiling snake. At one point she was hinting at moving due to Elaine, where the option of offering to move in the beach house was presented. The only other time where that option was presented due to a struggle was with Jolina due to financial issues. Elaine later mentions that she wanted Belle to be independent, which before wasn't hard for Belle to do, but now she is strangely paranoid about getting kicked out of the house, only for Belle later to confide in the MC about taking caring of her if she is kicked out. Jolina's a bit more interesting as she most likely is the accomplice of Belle, already with both of them on the PC, but Jolina is known to be somewhat good at PC security. Elaine's PC was once vulnerable, but then becomes protected, which Jolina could possibly have aided Belle to keep their plan safe. The fortune teller did say there was a plan or plot within a plot or plan. Jolina also had been with a very rich man, who could have been the father. It was revealed obviously that Jolina is lesbian since the fortune teller states the blonde is into women, and Teresa calls her a lesbian for denying her son, in which Jolina says she would always pick women than dog boy. Belle has mentioned she went down on women before, and I think I remember someone mention she says to MC of tasting familiar. Belle has quit her job and Jolina is already facing financial struggles on her business in which both will be in disaster if an opportunity doesn't pop up. An opportunity such as the son of a deceased rich man who has potential inheritance including a beach house, and a sister with her own will requirements that is trusting of her. I think Belle and Jolina are both working together using the vulnerability of Elaine and tricking the MC in order to fulfill their own will requirements and to get hella rich. With a backup plan of trying to go after the MC by hoping to live at the beach house and possibly have security due to the MC receiving money. She is already backstabbing her sister by trying to "help" with the will requirements for the MC while "being there" for her sister, which is pretty cold and deceitful. I think her will requirements include messing around with the MC in which she needs to persuade the MC into taking her in and possibly the main house too as the lawyer did mention the house being a castle.
It for sure can't be Monica and the other girls as the Lawyer makes it clear they are fine to know about the will requirements.
If it ain't Belle and Jolina, it might as well be Francois getting his revenge on the commoners casue I have no clue then