Lee know and Seungmin are known for having a divorced couple vibe, even though they don't hate each other it comes off that way to people but it's obviously all love. He does treat I.N nicer too but he's extra sweet with Felix for sure. And in a 2 kids room they couldn't really think of a time I.N and Lee Know hung out alone so I feel like that's where the difference lies between the two. Also you got the ages right except Hyunjin is older than Han :)