There is an existing wired system, but the customer wants to add a shed/outhouse onto their system. The panel is located at the front of the property, and you can’t wire an expander to the back of the building.
In this scenario you could add a local expander, such as WAP or W-XPR to the panel. Then replace the wired PIR at the back of the house for one of the new ‘R’ range detectors.
You could then add a detector/s in the shed and use the Wireless ‘R’ Detector to repeat the signal back to main expander.