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The mesomorphic behavior, shape shifting, and shape-memory types of two homologous series of main-chain liquid-crystalline co-elastomers (MC-LCEs) with composition-tunable transition temperatures and mesophases structures are reported. The weakly cross-linked macromolecules were prepared in a one-step procedure by the versatile platinum-catalyzed hydrosilylation reaction between siloxane oligomers (linear spacers and netlike point molecules) and liquid-crystalline binary mixtures, composed of defined proportions of divinylic monomeric mesogens. First, the two sets of alternated, linear copolymers with disiloxane or trisiloxane chain extender, respectively, were investigated. They either exhibit both smectic C (SmC) and nematic (N) phases or a single SmC phase, the nature of which being dictated by the length of the inserted siloxane moieties, and the temperatures ranges regulated by the composition of the mesogenic mixture (mesogens ratio). As anticipated, the thermal behavior of the corresponding co-elas...