Drogo is unsure if this is possible or if it would work as he hopes. As you know, you can cycle through the shop display options by right clicking the sign after the shop is created. Only if the shop is set to no display can you place another shop above it. Having shops stacked vertically is handy for space and it enables the use of hoppers to autofill. This can currently be done by starting with the bottom shop and working your way up, setting each shop to not display the item each time. The problem is when we want to change the prices, we have to break all the chests, dealing with the contents and start again from the bottom. See in this image where the new shop cannot be created as there is no space for the display item. If the display item was set to 'not display' by default, this might resolve the problem. Equally good, would be some way to edit the price with out the need of clearing the space above.