Found the answer here : http://blog.ivanti.com/obsessing-over-the-details-so-your-users-dont-have-to/?asredirect
May need to work on this as I can see on my own machine that OneDrive is taking the first 6 in the list so then I would assume that only the first 6 DataNow overlays will be used. This means that you still see the grey download icon and green ticks but not icons such as home and read only. Many users run OneDrive and DataNow so it is going to be tricky to please everyone...
Hi, you're correct in your assumption above. The limitation is the number of overlay slots provided by the operating system - the list is read in alphabetically from the top down - because the OneDrive overlays start with a double space, they get loaded ahead of the File Director overlays which only start with a single space, and the OS limit is reached part way through. With regards to your point around OneDrive/File director co-existence, We're actually introducing a OneDrive for Business connector in the next major release which will allow File Director to present a users' OD4B storage as a File Director Map point - In most instances this should remove the requirement for the OD client to be installed in tandem with the File Director client moving forwards - With that said, as per the blog, it's possible to re-order the list so that the most important overlays are displayed, by using a registry manipulation tool such as Ivanti Environment Manager