Okay, I spent most of the day working on this.
I would like to think that it wasn't wasted as I learned a bit about the Logic Block event.
There is a bug with DC. The Who Tries event works fine, but DC is not storing any values for thief skills, including backstabbing along one with the ones in the event. You can use a script to set a PCs thief skill to a number and that works with the Who Tries event.
The bug with DC is that it is storing null strings by default for the values of the thief skills.