Response from ST support
"I am really sorry but I will have to disappoint you. The smoke detector you have is not compatible due to the Z-wave architecture Fibaro have built into it. There are 2 models available the 001 and the 002, whilst the 001 is not compatible the 002 is (confusing I know). We also don’t currently support multi-channel devices such as the fibaro-fgs-221-double-on-off-relay-switch, and this would require a custom code to get it to work… As it is a dual switch you may only be able to get one of the switches to work.
The best place for getting the custom code would be the community, we have many of our programmers and engineers working along side fellow SmartThings users with custom integrations and automations. I have provided you a link to our UK compatibility list as well as the community."