Funny theory
Thread:

You have always believed that sejeong is just one person, but the true is they are Eightfold sisters, that's why she is so good at everything, because each one are good in something.

This is sejeong #1, she is the the most important because she is the one with the magnificent voice so she is who appears the most.

She is sejeong #2, she is the athletic one, good at sports and physical strength.

This is sejeong #3 she is the charismatic one, the funniest and the best in variety shows. Don't forget to support her in busted s3.

This is sejeong #4 she os the dancer... Or at least the one who dance better among them.

This is sejeong #5, the actress one. She is really good at this! I hope she can have another good drama based in a famous webtoon with pretty clothes and handsome actors.

This is sejeong #6, she is just good in pole dance, that's why she haven't appeared more. She disappeared but she is happy.

This is sejeong #7, she is the "manly" one or the ajussi among them. She act like a old uncle.

And finally this is sejeong #8, she is the cutest one, with the best aegyo. Just a cutie pie.