I am having so much fun with this drama. I love how the writer has created the Seo family. With the exception of the eldest son, all the other members have a perspective that is contrary to the usual kdrama families. How they view the world, situations and people is slightly off-center, but so refreshing and, yet, so on target. They really do think out of the box. They are are wacky, but good.
The cooking teacher's burn scars confirmed my suspicion that she is Yi Joo's mother. So, there will be lots to be revealed soon.
I also think that there's nothing wrong with Grandpa. I think he is actually hiding out in the nursing home for his own safety; away from the stepmother. I think he knows about the attempted poisoning and much more. But, he can't do anything about her because she know his dirty secrets and dealings.
As for the secretary, now, being in Yi Joo's camp, he probably wants to be in her 'tent'. The guy has had feelings for her for a long time. It's even possible that he has been, surreptitiously, protecting her through the years. However, she is either ignoring or so naive that she didn't get his innuendo when he said he didn't want money to join her camp. His reaction to finding out that she knew things about him is so cute. And, her demonstration of how he looked at favorite painting was hilarious.
We know what is her mission for the one year she's been given. But, we don't know about his mission, except that it must involve YJ.