If you've already got enough extra batting and backing, it shouldn't be too difficult to add more borders. You would have to unstitch a bit of the quilting on the last border to do so. The hardest part would probably be pressing the seams.
If you run out of matching fabric, you could always try to find a marble or other blender fabric for the binding. It's usually pretty easy to find something that blends and it doesn't have to match exactly.