Eg taken from Manhattan:
Wrong: Regina returned the dress to the store, which was torn at one of the seams.
Right: Regina returned the dress, which was torn at one of the seams, to the store.
In the corrected sentence, ", which was torn .." makes it sound like a non-essential modifier where as it should be an essential one because Regina might have brought 2 dresses home from the store out of which she returned the one that was torn and kept the good one with herself.
so, accoding to me, the corrected one shd be:
Regina returned the dress that was torn at one of the seams, to the store.
Is my understanding on this right?