  In this note we consider non-equilibrium steady states of one-dimensional
models of heat conduction (wealth exchange) which are coupled to some
reservoirs creating currents. In particular we will give sufficient and
necessary conditions which will depend only on the first two moments of the
reservoir measures and the redistribution parameter under which the two-point
functions are multilinear. This presents the first example of multilinear
two-point functions in the absence of product stationary measures.
