There are some good forum posts on re-creating the grid with your additional columns using BAQ Views. That could get you started, and is pretty easy. Jose even made a video!
Grid views that add missing (not hidden) columns will have some level of code needed.
Also, have you read the Epicor ICE Customization User Guide? It’s invaluable, and you can download it from EpicWeb.
Follow an example, get it to work, then tweak it for your changes. Hope this helps!