  Considering matter coupled supersymmetric Chern-Simons theories in three
dimensions we extend the Gaiotto-Witten mechanism of supersymmetry enhancement
$\mathcal{N}_3=3\to \mathcal{N}_3=4$ from the case where the hypermultiplets
span a flat HyperK\"ahler manifold to that where they live on a curved one. We
derive the precise conditions of this enhancement in terms of generalized
Gaiotto-Witten identities to be satisfied by the tri-holomorphic moment maps.
An infinite class of HyperK\"ahler metrics compatible with the enhancement
condition is provided by the Calabi metrics on $T^\star \mathbb{P}^{n}$. In
this list we find, for $n=2$ the resolution of the metric cone on
$\mathrm{N}^{0,1,0}$ which is the unique homogeneous Sasaki Einstein 7-manifold
leading to an $\mathcal{N}_4=3$ compactification of M-theory. This leads to
challenging perspectives for the discovery of new relations between the
enhancement mechanism in $D=3$, the geometry of M2-brane solutions and also for
the dual description of super Chern Simons theories on curved HyperK\"ahler
manifolds in terms of gauged fixed supergroup Chern Simons theories. The
relevant supergroup is in this case $\mathrm{SU(3|N)}$ where $\mathrm{SU(3)}$
is the flavor group and $\mathrm{U(N)}$ is the color group.
