Uhh

In korea middle schoolers can be 16 in their last year im pretty sure

I'm pretty sure they are just like 1 year apart

I could be wrong

In South Korea highschool grade are different from the US, it goes from is 10th - 12th grade, while middle school is 7th - 9th.
I'm assuming or guessing that Chowon's and Kyungsoo's daughter is a 9th grader.

Def 1 year apart based on side stories. Cus I'm pretty sure byul was atleast 2-3 years old by the end of it.

Yeah it's kinda confusing but maybe the age will be clarified at some point

Hm I hope so but it's still kind of weird having a crush on the daughter of your adopted dad's ex shit if I were her dads I'd be so disgusted

Why tho? That has nothing to do with them, they are happy children and have good parents that wouldn't let that affect them

For one thing, they aren't related.
Second, they aren't family or anything(like cousins or something), third is that there's no sibling dynamics and fourth, their parents' problem(that got resolved) is none of the kids' business. In the first place, her beta dad has a don't give a fuck attitude about his husband's ex wife(?)/husband. Even attended the wedding smugly, so I doubt he'd ever have a problem cus the beef is all gone and i bet it would stroke his beta ego if his daughter hook up with his husband's ex's daughter. Meanwhile, her alpha father is way too chill and never brought up how weird it is his husband attended his ex's wedding.

At this point, idk what is supposed to be "weird" about their crush. Maybe there could be drama from judgmental people outside the family in the know of their past drama but fuck em, it's not their right to judge. In the end, it's just an innocent childhood crush.