Responses
yeah that my most best speculation. thanks for the clarification.
i still think it's a stretch to call hajin's stole the older one's life. after all why couldnt they both life in luxury?? why one has to be thrown?? even if there is a reason it wasnt hajin's fault. i mean i think the drama is being too overboard just because. i rather they have the usual he actually an illegitime child. ok maybe not, but it will make more sense.
btw the timeline explanation about who was born in england and who had to stay in korea still doesnt make sense. the translation also responsible for it.

the problem is idek that the story about born in england is accurate, there's just something didnt click bad translation, what clear is
- baek hayoon is actually the older brother and supposed to be named hajin, but the whole world think he is the youngest even manager kim.
- hajin is actually the younger one
confusion:
- is one of them illegitimate or half brother? i feel that both are real from the same parents. the mom's word "you know what he is to us" and the grandfather word, "you are my only grandson". if one of them is lying or don't know it most likely the grandfather. also hajin said he was the outsider. it may mean he is the illegitimate son or he is just the black sheep of the family that his mother dislike. and if he is illegitime, he related to whom? i still think he's the mother's son by her past words but also looks so much like dad. and there's little chance the dad will make someone not related to him by blood as his successor (unless he doesnt care about blood). it's more likely he was an orphan and not related to anyone. or he actually still the son but just disliked by mom.
- the timeline. it's said mother gave birth to older son who then was left in grandparents' care. them later she gave birth to another son in england. Manager. Kim said the first time he met Hajin was after he returned from England... but Hajin was the older one in his eyes so he wasnt supposed to be the one from England in Manager Kim's head.... is this translation error?? and if original hajin jas busan's dialect then isnt he the one who was left in grandparent's care thus it means he's the oldest. except if that video isnt actually hajin but baek in black hair. the timeline is what mess the explanation up.