Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a relay user equipment (UE) may detect, on a sidelink, a sidelink transmission that carries a transport block (TB) to be forwarded to a base station. The relay UE may detect, on an access link, an uplink transmission that carries the TB. The relay UE may generate a message that includes the TB to be forwarded to the base station, wherein the message includes data associated with the TB that is obtained from one or more of the sidelink transmission or the uplink transmission. The relay UE may transmit the message to the base station via the access link. Numerous other aspects are described.