The negatively charged silicon vacancy (V-Si(-)) in silicon carbide (SiC) is a paramagnetic and optically active defect in hexagonal SiC. The V(Si)(- )defect possesses S = 3/2 spin with long spin coherence time, and it can be optically manipulated even at room temperature. Recently, electron spin resonance signals have been observed besides those associated with the V-Si(- ) defects in the 4H polytype of SiC. The corresponding centers share properties akin to those of the V-Si(- ) defects and thus they may be promising candidates for quantum technology applications. However, the exact origin of the new signals is unknown. In this paper, we report V-1-related pair defect models as possible candidates for the unknown centers. We determine the corresponding electronic structures and magneto-optical properties as obtained by density functional theory calculations. We propose models for the recently observed electron paramagnetic resonance centers, and we predict their optical signals for identification in future experiments.