Ok took a bit of time with the bank holiday & bit of a learning curve to understand what is going on but here we go…
My modified version of the Hive (Connect) SmartApp: https://github.com/Bibbleq/SmartThingsPublic/blob/master/smartapps/alyc100/hive-connect.src/hive-connect.groovy
And a new DH to add for the TRV device type: https://github.com/Bibbleq/SmartThingsPublic/blob/master/devicetypes/alyc100/hive-TRV.src/hive-TRV.groovy
Copy the smartapp code over the top of your current “Hive (Connect)” one and then make a new DH from RAW code for the TRV bits.
Go nuts, let me know what you find & don’t blame me 
Edit: Think if a TRV is in schedule mode adjusting the set point isn’t working right…