i don't think this is a part of any plans bc why would the assassin go to the extent of killing deokjae to make sure jihwa wouldn't get affected, only for jihwa to go and put himself in harms way? and it seems like jihwa doesn't know about what happened to deokjae at all because he says, "it's nerve wracking enough with that servant fellow in on it." how could the assassin have told him about a whole new strategy if they haven't even seen each other? idk, i just can't see the assassin using jihwa as bait.
But then again Jihwa made it look like it was a letter from Lord Song so initially, he wouldn't have been involved but Seungho found out that it was Jihwa through the handwriting (how dumb are you Jihwa) and went to go find Seungho instead.... but either way Seungho's out of the house and poor baby Nakyum might be in danger.
*went to find Jihwa instead
is jihwa purposely making seungho out of the house? huhue no name gonna come at nk now? nooo