Sorted

We have two solar powered Velux windows and we got two controllers when they were fitted.
One controller operates both windows.
The duty unit has become more and more difficult to operate as the touch screen seems to be getting less reliable. Programming the unused unit should have been simple but the info in the book is very sparse and tells what you can’t do rather than what you can.
Thankfully Velux tech service in Scotland came good and the new unit is working the windows automatically now.