  We study the general deformation of $\mathcal N=2$ supersymmetry
transformations of a vector multiplet that forms a (constant) triplet under the
$SU(2)$ R-symmetry corresponding to the magnetic dual of the triplet of the
Fayet-Iliopoulos (FI) parameters. We show that in the presence of both
triplets, the induced scalar potential of a vector multiplet with generic
prepotential has always a minimum that realises partial breaking of $\mathcal
N=2\to \mathcal N=1$ supersymmetry. We then consider the impact of the
deformation in the Dirac-Born-Infeld (DBI) action where one supersymmetry is
non-linearly realised, described by a nilpotent constraint on the deformed
$\mathcal N=2$ chiral-chiral superfield. We show that the generic magnetic
deformation induces an ordinary FI D-term along the linear supersymmetry via
the theta-angle. Moreover, we argue that the resulting action differs on-shell
from the standard one (DBI+FI) by fermionic contributions.
