I'm not sure what you mean by "include a mid-route destination".
As Marvin has pointed out, with iGuidance you will never ever get routing directions past the first point in the itinerary. So, by that definition, you can have an itinerary with ten points in it but you'll only ever see the route calculated and displayed onscreen from where you are to the next point in the itinerary, and directions provided for only that section.
You will never see the route for the total itinerary, from starting point to final destination, displayed onscreen nor will you ever see directions for the total itinerary. iGuidance simply doesn't do that. It calculates routing, displays the route onscreen and provides directions from where you are to the next point you have identified. That's it.
When iGuidance detects that you are at that point, it will ask if you want the routing and directions to the next point. That's the only time, and the only way, you will ever see the routing onscreen and directions for anything beyond that "next" point in the itinerary.
That's why Marvin keeps telling you that the only way you can honestly test it is to go for a drive with it. Set a multipoint itinerary to, say, a couple of stores or donut shops in the area and head out. Once iGuidance has a satellite lock and is ready to roll, you'll see the routing onscreen to the first point. When you get there, you'll get the routing to the next point, but not before that.
Is that what you are getting at?
Or are you saying that you can't even create an itinerary with more than a single point in the list?