Well the Quick Link was designed and built to solve those type of irrigation problems. With one good zone wire plus the common wire you can control 2 zones or 4 zones. Not only that but unlike the Doubler the valves can be programmed differently since they will not constantly change zones. The two parts to it look similar but one is the transmitter and the other is the receiver. Using the transmitter at the controller the functioning zone wire is wired into its lead and the 2 or 4 spare wires from the transmitter are used on the empty terminals or to replace no longer usable wires. The receiver is placed in the field and the same procedure is followed there. Now you have bypassed a pesky broken wire or added zones for a new bed in the landscape. Its a big money saver for the customer and a big time saver for you.