  Applications where multiple users communicate with a common server and desire
low latency are common and increasing. This paper studies a network with two
source nodes, one relay node and a destination node, where each source nodes
wishes to transmit a sequence of messages, through the relay, to the
destination, who is required to decode the messages with a strict delay
constraint $T$. The network with a single source node has been studied in
\cite{Silas2019}. We start by introducing two important tools: the delay
spectrum, which generalizes delay-constrained point-to-point transmission, and
concatenation, which, similar to time sharing, allows combinations of different
codes in order to achieve a desired regime of operation. Using these tools, we
are able to generalize the two schemes previously presented in
\cite{Silas2019}, and propose a novel scheme which allows us to achieve optimal
rates under a set of well-defined conditions. Such novel scheme is further
optimized in order to improve the achievable rates in the scenarios where the
conditions for optimality are not met.
