You could go out and invest $4k bucks on a repeater and put it on a well placed site with a 200' high antenna and the guy down the block could grab 2 mobiles and stick a repeater in his back yard on the same channel and there is nothing you can do. You can try to work it out but if you cant nobody can help you. Operating simplex on a repeater output would be the proper way to use simplex on GMRS, this results to what is known as talk around. Several repeaters can co exist on the same channel as long as everybody is using a different pl/dpl the only time its going to be an issue is when both are transmitting at the same time, the better repeater most always wins. GMRS Operators tend to work together and solve most interference issues unless one is a total jerk. Corey