I reckon there might be one more family member they're either keeping secret or who's hiding themselves. The show hasn't dropped any hints about this person yet. But if you check out the drama poster, it shows six family members, not including Do Da Hee. So, we've got Bok Gwi Ju, Bok Man Heum, Bok Dong Hee, Bok Yi Na, and Eom Soon Gu. But there's someone else in the picture; you can see their shadow and hand. It looks like the shadow's holding a gun to their head. Or maybe, I could be off track, and it might actually turn out to be Bok Yi Na's birth mother. We might catch a glimpse of this mystery person in the next episodes, though.
Here's the link:
https://kisskh.at/photos/Z8k6dL_4