I've run out of time researching/documenting my rationale, but here are my current theories/predictions:
1. Da Hye is Mistress Bitch's daughter (1st clue - the wreath ceremony) and sibling of Eunseong. She is fake - but then, who is her fake brother?
2. Grace does not realize that Eun seong is the son of Mistress Bitch and doesn't realize that Mistress Bitch is the ultimate mastermind. (The one reason I am not positive about this is her statement to eun seong that she was "only following orders" when she plotted the whole wild boar incident. Who gave the orders?
3. The conspiracy began when Eun Seong lost his Queens Scholarship because he killed the dog.
4. Eun seong will eventually claim that he was the one who saved a young Hae-in at the beach, but in fact, it was Hyun woo.
5. My perennial prediction - when they become pregnant (and I do mean THEY), it will be twins. I've been more right on this than wrong because I'm a twin mom.
After the weekend (ep. 7-8), we'll see how many of these become totally null and void, lol. ???