Transition-metal-based kagome metals are of significant interest due to their potential to host a wide range of electronic instabilities. The unique electronic frustration arising from the triangular and hexagonal atomic arrangements in these systems gives rise to features such as Dirac nodes, van Hove singularities, and flat bands, which in turn can bring about topological phenomena, superconductivity, and charge-density-wave (CDW) induced superstructures. Among these materials, the hexagonal HfFe₆Ge₆-type compounds form a large family characterized by two kagome layers per unit cell for which the ScV₆Sn₆ system is a notable exception, as it exhibits a CDW with a 3×3×3 superstructure below 92 K. With our high-resolution x-ray diffraction experiments we will demonstrate that upon cooling from room temperature, diffuse peaks corresponding to a 3×3×2 superstructure occur and gradually intensify as the system approaches the phase transition. Directly at the phase transition, a competition is observed between the 3×3×2 and a 3×3×3 CDW, with the latter ultimately prevailing below the transition temperature. Furthermore, we will show how both CDWs are progressively suppressed by Cr substitution, eventually becoming completely incoherent. For a Cr concentration of approximately x = 0.06, this suppression finally leads to the emergence of a quantum critical point in Sc(V₁₋ₓCrₓ)₆Sn₆.