∀ {D : Type u₂} [inst : CategoryTheory.Category.{v₂, u₂} D] {S' R : CategoryTheory.Functor Dᵒᵖ CommRingCat}
  (φ' : S' ⟶ R) {X Y : Dᵒᵖ} (f : X ⟶ Y) (x : ↑(R.obj X)),
  (ModuleCat.Hom.hom ((PresheafOfModules.DifferentialsConstruction.relativeDifferentials' φ').map f))
      (CommRingCat.KaehlerDifferential.d x) =
    CommRingCat.KaehlerDifferential.d ((CategoryTheory.ConcreteCategory.hom (R.map f)) x)