As complexity goes, this is on the simpler end of the spectrum. What experience do you have? It's going to be a lot easier to leverage off things you do know how to do, rather than imagine what you can/cannot do.
Most of the Who Transmits and Who Receives is determined by the main() loop, cutting all the transmit management from the listening units should provide more clarity. If the primary station doesn't listen at all, the reception management can be dispensed with. The listener doesn't need to respond, it can go into the idle state, and then continue listening.
Comment out large blocks of code, or use #if / #endif pairs, to trim code whilst you determine what's critical and what's not.
>>can anyone help regarding this case keeping in mind that I am new to this field.
There are places like https://www.fiverr.com/ where you can get help and work done on your project.
