This is also a big worry for me.. I tried several times to find an easy way to identify European Diamond Owners... but there is just no simple way.
Yesterday I talked to the German Diamond maintenance center.. asked them if they could distribute it to their customers.. they were aware of the survey but have not planned proactive steps to make customers aware.
It would be an easy thing for Diamond to reach out to all of their certified maintenance partners (the ones that can order spare parts) asking them to inform their customers..
I would assume, that there are more DA40 and DA42 flying in Europe than in the US...
Maybe a good point to discuss with Diamond in your next meeting on how to reach out to European customers..