can you add VWG to regular bread flour to make hi gluten?

Honestly, a great deal of recipes that call for high-gluten can be made just fine without the VWG. It just depends on how faithfully you want to re-create the recipe's crumb texture. A lot of folks actually bring the protein content down by adding some all purpose flour, which creates a much softer and lighter crumb.

If you are reasonably experienced with handling different degrees of gluten in a variety of doughs, you can try it without the VWG. I'm sure you'll get it developed, shaped, and into the oven without a disaster. You're not going to get the exact same crust, crumb, or mouth feel, but that isn't necessarily a bad thing.

There are a few rare exceptions where the VWG is definitely necessary for the structure of certain freeform loaves. You can probably tell by the recipe whether or not the VWG is being used for proofing structure, or just end product feel.

- Keith