The fact is, it's quite difficult to align spatially a DVD and BD, because 99% of the times crop is different, often from scene to scene or from shot to shot... what if, for example, you have the DVD covering just 90% of the BD image area? You'll leave four borders with BD color?

I must admit I haven't tried myself with this very title, but I'm almost sure it is like I suspect, or the project probably emerged some time ago... said that, it's still possible to color grading the EE BD using EE DVD as reference, but results may vary...