I think he's going to marry the spoiled girl, bec he's after being accepted by his family members and ppl from their business (they think Ijun is better suited for being the heir of the business) even if he lost the 1% he has better voice in their company if he marry the "real" daughter. Im just waiting for the grandfather to know everything bec i think he, like Ijun, think of Siyeon like family

I dont think I can wait 5 years seeing this bitch get spoiled by both parents. I pity FL, but she should come clean to Ijun, not the part traveling back in time, only about being switch with that bitch. He would deffinitly connect dots seeing that FL is resembling her real parent (hanam parents), and the bitch is resemling Ichon parents. And this new guy (forgot the name) imo he is friend with the bitch for bussiness sake of his parents. Gwihyeon is getting more ambitious, still I can't figure out who will he end up with, but it's probably with the bitch for bussiness sake too. And Hanam parents idk if they know about their real daughter or are in dark (I came back to thi manhwa after break so I do'nt remember), but if the FL approaches them and come clean, they would forsake the bitch and spoil our FL, and then she can be happy.
Sorry guys for forgotting names of charecters, but it's hard for me to remember. I used to read mangas (japanese) and then manhwas. For me japanese names are easier to remember then koreans.
Season 1 ends with chapter 43.