The prime focus of this work is in developing a protocol for a symbiotic architecture called Cognitive Relaying with Time Incentive for Multiple Primary Users (CRTI-M). The rationale of CRTI-M is that the Primary Users (PUs) of a Cognitive Radio (CR) network, with weak transmission links, seek cooperation from the cognitive Secondary User (SU) nodes in their vicinity, and in return reward them with an incentive time for their own communication. Each PU has its own distinct bandwidth of operation; however, when relaying through the SU network it can use the bandwidth of the other PUs as well to enhance its throughput. A cross-layer optimization problem is formulated to that effect in a multi-hop multi-channel SU network. The time incentive that should be awarded to the SUs by each PU is analyzed by means of a utility-based decision-making process, and its efficient utilization is proposed. To make the CRTI-M scheme practically realizable, a MAC scheduling protocol is devised within a unified framework of the PUs and SUs. Simulation results are furnished to demonstrate the proof of concept.