Sorry, busy with other things.
If you are using PWM inputs on RC#1, then you simply add the other receiver from RC#2 and use say the throttle channel from RC#2 receiver and transmitter as if it were a knob or slider on RC#1. Those connectors only have one wire, so you will need to somehow get power and ground to receiver#2.
Thanks, that's clear, I have a spare 5volt on the PCB I can connect to the second RX it takes from 3v to 7.4volt ( lemon RX dsmx diversity ). I really love these Lemon receivers. They are very high quality and the 6channel Diversity was only 15$ and are extremely lightweight.