How to add a recolour under the original item..?

This may be a bad question, but when I recolour lets say just a simple shirt that was in original sims, I want it to appear as a colour with a custom thumbnail under the original shirt. I don't want to have another catalog thumbnail for it, it should just appear as selectable colour under the original.

Is this not possible? Am I missing something? I tried looking through tutorials but they just go like 'select this' and not really discussing the options within the program. Started very recently.