In this paper, the authors investigate the performance of Low-Density Parity-Check (LDPC) product codes in a multisource relay network where multiple sources transmit data to a same destination with the help of a noisy relay. They consider an LDPC product code resulting from the concatenation of Multiple Serially Concatenated Multiple Parity-Check (M-SCMPC) codes. Every source encodes its data using the same M-SC-MPC code and broadcasts the codeword to relay and destination. The relay decodes and stores all codewords from sources in the rows of a matrix and encodes the columns using another M-SC-MPC code. Only the redundancy part generated by the relay is forwarded to the destination.