A couple of ways but all require a "middle man" 1st requires no extra device but adds a delay. Thats to include IFTTT. So broadlink app then pushes to IFTTT as a light, then tou create a virtual switch in ST and link them. IF smartthing switch turns on THEN broadlink switch turns on and the same with off. The virtual switch is shareble with alexa if you want that Second is to use a android device as your middle man, and install RM bridge and the device handler by beckyricha as posted above. This way is more local as it cuts out the broadlink and IFTTT servers and operates on your LAN so its much faster at responding. There are other was to do it including home assistant or node red but ill leave those for now. And the alexa routine posted above that i have not tried as i use google, however its pretty much the same idea as the IFTTT one