HDX Metal Shelving Connector

Do you like HDX metal shelving, but they don't make them tall enough? I had two sets of HDX shelves from Home Depot. The dimensions of the shelves are 37 in. H x 36 in. W x 14 in. D. I'm guessing the shelves are only sold with a maximum of 37 inch height for stability/safety/legal reasons--smaller footprint + greater height = less stable.

I really wanted to stack these shelves, but I couldn't find any "official" way to stack them safely. The bottom of the posts have welded, threaded holes for