Responsibility for safety and maintenance
The grave owner is responsible for the safety and maintenance of the memorial.
If a memorial becomes dangerous, we may take whatever action is necessary to make it safe. This may mean removing it. We may reclaim any costs we have to pay in doing this from the person who holds the rights to the grave.
It is always a good idea to insure a memorial against accidental damage and vandalism. You should make sure the cover applies as soon as you put it up.
You can get information about this from a memorial mason or the National Association of Memorial Masons.