I have been asked quite a few times in my job as a Security Consulant, "Can Mars make use of my exisiting Qualys or Foundstone Appliance?"
Well yes, we can grab all the information that the 3rd party vulnerablilty scanner, knows about your network, and import this into the MARS database.
As you may already know, MARS has a built in Nessus scanner, and will use this (optional) for false positive analysis on incidents.
But using your exisiting VA will also add value, and save you time in manually configuring the OS, and Services running on your assets.
See below...