That's the same remote that came with my Dave.just to be clear, I am attaching a pic of the remote I am currently using with both my DAVE and Blu MkII. Chord has confirmed with me via email that this remote cannot be used to set both units to sleep. I tried the instructions above by using the HiFi and AV button but even then I only seem to be able to put the DAVE to sleep and not the Blu MKII.
Irrespective of any instructions ever written by anyone, on my remote both the HiFi and AV buttons activate Dave. Which implies they won't be able to activate anything else.
Seems like a poor choice to me, but there you go. I guess this is a generic remote with a Chord badge on it, so you get inconsistencies typical of using generic remotes for specific purposes.