I use a fibaro dual relay to control one of
http://installers.velux.co.uk/V-GB/Installers.nsf/KLF%20100%20-%20451719-0109.pdf?OpenFileResource. My use case is to globally close 4 blinds triggered off my DSC Alarm and schedules. It becomes expensive if you want to control blinds individually or in rooms (I can still use the room level remotes that allow you to group blinds). I also only use them to fully open and close the blinds. I did find examples where someone had hacked the relatively cheap remotes by soldering a relay onto the switch contacts but at the time I didn't want to trash them (I may well try at some point and use relays attached to a raspberry pi).
The fibaro is configured to automatically switch off after a short delay and the two devices are mapped to a virtual device with an on and off state and they work really well controlled with the Alexa plugin as well.
Check out eBay as I recall I got mine at a reasonable discount (you can also get the remotes if you wish to try the hacking version).
Let me know if you need more, I recall the setup is a little freaky for the interface.
Thanks
Neil