  We consider a compressible flow structure interaction (FSI) PDE system which
is linearized about some reference rest state. The deformable interface is
under the effect of an ambient field generated by the underlying and unbounded
material derivative term which further contributes to the non-dissipativity of
the FSI system, with respect to the standard energy inner product. In this work
we show that, on an appropriate subspace, only one dimension less than the
entire finite energy space, the FSI system is wellposed, and is moreover
associated with a continuous semigroup which is \emph{uniformly bounded} in
time. Our approach involves establishing maximal dissipativity with respect to
a special inner product which is equivalent to the standard inner product for
the given finite energy space. Among other technical features, the necesssary
PDE estimates require the invocation of a multiplier which is intrinsic to the
given compressible FSI system.
