"Just bought my first Vidmar last week & would like to add the "only one drawer open" feature."
Have 9 Vidmars, a couple came with the one drawer open option. Personally it is a royal pain in the ***, slowing down my quick access to multiple draws, open and closing draws quickly searching for items. Without the feature you get used to not opening more than a couple drawers at once. It really does slow you down as each drawer must be fully closed before another is opened, slightly ajar (which is common on closing a drawer) and you have to stop and check, also when the drawers close, other drawers come ajar, royal pain. If you have kids around it might be a good idea, but you can also attach the cabinet to the wall. You could possibly purchase the present one drawer option hardware from Vidmar, but it would not be cheap even if the option can be purchased for your Vidmar model.