After googling this, seeing a hint of your question and then having to register to this forum just to see this post I was really hoping there would be an answer here.
I just spent 300 euros on TRV's and am wondering this myself. If I go away, I'm going to have to go to each individual TRV and set it to holiday mode. Not to mention that to manage each device from the webapp I have to open each device in it's own page after looking up the IP address. Oh, and the webapp is limited compared to the android app.