Very simple READ the Tech doc on the RTI WEB site - 1 REMOTE can only have One parent . Parent = zm24 . ZM24 can have many children . you CANNOT roam between parents . Design you systems by TESTING the site first . This will involved investing in some money in RTI but will solve all the issues and your money in the future . Going back cost you money and the RTI Story is get in get out . The tools for testing zigbee are on the dealer section . if the client doesn't really need two way then 433 is your best friend ! it works and it will ALWAYS work in a 1 way solution . some times technology makes us go 2 steps forward 3 back . mmmm is the light on or is it off ???