I do not own Dimenstion Strings, but there is absolutely no doubt that this behavior is 100% produceable (play a chord, and it splits the notes). All you have to do is build your own simple cell matrix and it will do it automatically. The only requirement necessary to do this is VI PRO. I do not believe the free version does auto-division of patches.
If you have VI PRO (I am no in front of my DAW) you simply load up 4 different patches of the 2 chair divisi sections, then go to the Voicing tab and tell it how to behave with 2 notes, 3 notes or 4 notes. You can set it up to do things like, if I play 3 notes, Patches 1+2 are note 1, Patch 2 and 3 are note 2 and 3. Or if you play 2 notes, Sections 1 and 2 play note 1 and 3 and 4 play note 2.
I also know they made a video on this to show you how to set it up. I believe it's the VI PRO demonstration videos, not the "samples" videos. If you go to PRODUCTS, SOFTWARE, choose VIENNA INSTRUMENTS PRO on the left of the screen. Then choose VIDEOS. Watch the one called AUTO-VOICING. As you can see, you can do auto divisi of ALL VSL products.
Hope that helps.