Thanks, not it wasn’t a typo. I was assuming it was not bidirection 2 wire AC as how could that work?! :O)
What that will give me is one set of AC lines that will turn on or another unconnected set? So, I can connect those up to two separate DC 24V power supplies and put some diodes on the outputs of those to make sure they don’t feedback into each other when I connect them together and power the polarity reversing DC window motors (with internal limits as well). That should work shouldn’t it? It just gets me around having to use more than one DBMZ and I can use a couple of relatively cheap DC power supplies (found some for £20), plus we won’t have the DC power supplies running all the time so standby should be even better (something I notice that is not mentioned on the sheet that compares them to the Somfy solution)