  We study communication between an inertial observer and one of two
causally-disconnected counter accelerating observers. We will restrict the
quantum channel considering inertial-to-accelerated bipartite classical and
quantum communication over different sets of Unruh modes (single-rail or
dual-rail encoding). We find that the coherent information (and therefore, the
amount of entanglement that can be generated via state merging protocol) in
this strongly restricted channel presents some interesting monogamy properties
between the inertial and only one of the accelerated observers if we take a
fixed choice of the Unruh mode used in the channel. The optimization of the
controllable parameters is also studied and we find that they deviate from the
values usually employed in the literature.
