If anyone is interested, I created a stateless Capability Alexa Virtual Device:
This is stateless, ie you can turn it on when it is already on and so on; the same goes for the sensors.
It is a switch (which triggers the contact sensor) and a dimmer (which triggers the motion sensor).
I needed it as I had a single device with a high and low mode selector, as well as the on and off… hopefully it can help someone else as well!