At least in my case, no you can't.
First, using multiple different vendor graphics cards, while theoretically possible, is riddled with problems.
This part has been asked before, but I can't seem to put my hands on the question
Second, most of the time on-board graphics is disabled when the motherboard detects a secondary video card inserted.
Third, even if it were possible you would run in to similar issues to what vga_switcheroo, bumblebee, and ironhide all try to address.
While they are a little different since they address hybrid graphics cards, I would imagine there would be similar problems.