Developing nanomaterials of previously unavailable shapes and compositions continues to be a key need and interest in nanotechnology. Copper sulfide based semiconductors are particularly interesting in this regard, because of the many possible copper sulfide phases, the appearance of localized surface plasmon resonance in copper-deficient phases, and the ease with which copper sulfide phases can undergo cation incorporation or exchange to produce new binary, ternary, or even quaternary materials. Understanding these cation incorporation processes has become a major emphasis in our research group. In our recent studies, we prepared unique biconcave djurleite Cu_1.94S nanoplatelets (NPls) from template CuInS₂ (CIS) NPls via a cation exchange (CE) reaction. We incorporated indium and tin into Cu_1.81S-ZnS sandwich-like nanoheterostructures (NHs). The selectivity of cation incorporation depended upon both the cation itself and the hetero-domains in which CE reactions take place. These studies not only provide a better understanding of the relationships among composition, morphology and crystal structure for copper sulfide-based nanocrystals, but also provide new pathways to previously inaccessible morphologies, compositions, and heterostructures.