Good you have all sensors inside the HA device - and this functionality was added recently 
Open the device settings for the cover device. Then you can check these checkboxes:
First one adds device sensors, secons one adds additional diagnostic sensors.
This way, your sensors should be added to the existing device.
If you want to trigger flows for these additional sensors, you have to use the “capability has changed” flow trigger and select your capability in the card.
Some details you can find here:
But you can also add them as standalone sensor devices. It’s up to you 
