The writers need to cut big Sister a break already...this is so unfair

Hahahaha couldn't agree more. Even in the upcoming episode 13 she still suffers 

What's up with this Jang Mi/ Jiwoo paternity thing? Is Sangjun really the father? And why do I feel the photographer/cousin has underlying evil schemes?

He did say Aunty did him wrong by stealing his inheritance and then acting all benevolent with his funds. He is upset about and being put upon by aunty. He is definitely planning revenge.

Ji Woo. How many DNA results did his despicable Dad Young Sik mess with while claiming he’s concerned about Ji Woo.