Well, I'd use Color and use the secondaries to isolate the two guys and brighten only them, tweaking everything to get it right. Explaining exactly how to do this in a forum, when you don't know Color, will be impossible. If you knew Color and read about how I would do it, you'd understand.
You do want to use a tool like Color or Resolve Lite or Colorista that allows you to isolate the people. Explaining step by step would be like writing a manual.
You can use the 3 way color corrector to isolate the white and blow it out and remove any saturation. Then use another 3 way color corrector filter to bring the now uniform white down to 100 ire, bring down the black levels to 0, and pump up the saturation of the subjects.
Works on this shot as a still pretty easily, but moving video might be something else. Other shots might be different too, especially if someone has a white shirt.
But you're probably just best off sending them out to a colorist or at least an editor that knows davinci or color or at least the above technique in 3 way CC. Like Shane said, it'd be like writing a manual unless you kinda have the idea already.