Who do you think is going to find out first? SJ or SY and why do you think that? 

I dont see why SJ doesn't recognize her first. you shouldnt forget your mothers face she was old enough to remember her. SY hasnt recognized her because she was a kid so her face has changed a bit also the name change is a factor. SY is looking for a woman named Soo Kyung so Soo Ji isn't who she would think could be her daughter. the yellow knitted sweater was semi revealed to her though.

I am literally thinking of the same thing. Even for SY, don’t mother sense their children? She couldn’t recognize the resemblance of SJ to her own daughter? You know what’s funny, whenever SJ has flashbacks, her mother is always blurry which shows she has vague memories of her mother. Also what I find interesting, SJ couldn’t recognize her mother’s voice? Anyhow, a lot of things are weird and so make this birth secret quite unbelievable.