  We use an infinite-range Maier-Saupe model, with two sets of local
quadrupolar variables and restricted orientations, to investigate the global
phase diagram of a coupled system of two nematic subsystems. The free energy
and the equations of state are exactly calculated by standard techniques of
statistical mechanics. The nematic-isotropic transition temperature of system A
increases with both the interaction energy among mesogens of system B, and the
two-subsystem coupling $J$. This enhancement of the nematic phase is manifested
in a global phase diagram in terms of the interaction parameters and the
temperature $T$. We make some comments on the connections of these results with
experimental findings for a system of diluted ferroelectric nanoparticles
embedded in a nematic liquid-crystalline environment.
