Hi, there is already a smartapp for that… It’s called ScheduleTstatZones and it’s designed to manage multiple thermostats with the concepts of rooms/zones/schedules…
You elect one thermostat as the master and you can specify all the slave thermostats in your rooms/zones to be controlled…, And you can control each of your zones with virtual zone devices (using a single tap).
I’ve just released a new version:
Refer to the ST community wiki for more details about the features and use cases supported (under the supported features and configuration sections):
http://thingsthataresmart.wiki/index.php?title=ScheduleTstatZones#Supported_Features
http://thingsthataresmart.wiki/index.php?title=ScheduleTstatZones#Configuration
P.S. The smartapp has many features and to do something similar with webcore would be impossible (more than 4500 lines of code).
Regards.