Answer

It is possible to process plating to the surface that is already plating finished surface. For example, it is possible to process chrome plating on the already chrome plated surface. It is also possible to process chrome plating on the nickel plating processed surface, or nickel plating or chrome plating on the copper plating, as a different plating combination. On the other-hand, there are some difficult combination of plating. For example, if you process nickel plating on the nickel-plated surface, the plating coat will have very poor adherence.