I want to see all of her family and how they were affected, I imagine the mother isn't doing to well and seeing her reincarnated daughter wouldn't go great but if the sister finds out it might not be so bad
Spoiler about her sister to those who might want it:
She's not the 2nd FL. Besides the fact that she feels sorry for Seoha because he's so hung up on the past, she's trying so hard to approach him because she likes secretary Ha.
Ummm, sorry to say this but there is basically no info right now that you could base that on. And some other commenters seem to have the exact fear
Obviously, people are conditioned to instantly associate the second female introduced in there types of stories as the rival. Certainly the genre tropes don't help with this, but please try to have an open-mind. A good author will always try to break the mold of the tropes and I am always looking forward to that
...besides, the secretary seems to have a history with her, so my intuition tells me he will be involved with her instead.