I see what you mean that figuring out what the different selections mean COULD be complicated, but then again, I would think that most of the time, checkboxes and multi-select list boxes would be used as independent choices - do this if option1 is checked, do this if option 2 is checked, independent of each other. Wouldn't really be any different from the way the combo box is handled, except that the user may have more rules applied.
Not having this is a big problem for me, and I am kind of miffed that it wasn't documented anywhere. I specifically checked for this before I purchased the software, and since nothing in the documentation indicated it couldn't be done, it appeared that I would be able to do that. Now I've told clients I can do it, and I'm up a creek.
Does the enterprise edition come with source code? And would the basic use-case, as above, be a difficult code change?