  We propose an uni-parametric deformation method of action principles of
scalar fields coupled to gravity which generates new models with massive
stealth field configurations, i.e. with vanishing energy-momentum tensor. The
method applies to a wide class of models and we provide three examples. In
particular we observe that in the case of the standard massive scalar action
principle, the respective deformed action contains the stealth configurations
and it preserves the massive ones of the undeformed model. We also observe
that, in this latter example, the effect of the energy-momentum tensor of the
massive (non-stealth) field can be amplified or damped by the deformation
parameter, alternatively the mass of the stealth field.
