Hmm, trying to add a yes/no menu to the dialogue seems to be flaky in the game code. I'm only seeing ONE instance of them doing a dialogue within a dialogue option, during the Demon Prince Hermes fight. I also notice the developers REALLY struggled on this one as they not only wrote functions for it, but even an entire supporting script with debug code. I can probably put that in, but I can't guarantee it will work as it seems the devs themselves were unsure of it.
Well in either case what I'm working with is the source code, so pretty much anything is possible... It just changes how much time is required to get it working right.
It would definitely be much faster to have it be one OR the other.