Q: Why does the duvet move around inside the cover ?

A: There are many reasons which can cause the gap between the duvet and cover, this shifting which can be very annoying while sleeping.  Most but not all Down Under Bedding Brand duvet & comforters have a built in corner ties to attach to the four corners of your duvet cover to help end the nightmare.

Kind of like shoes laces as you attach the duvet and cover to stay tight and snug.

Yes we also carry the matching duvet covers with corner tie tabs so you don't have to sew.
Sleep tight