We are in the middle of migration, a full backup has been taken and copied to destination. On Friday, we plan to do a differential, but someone by mistake did another full backup (did not use copy_only). 

We want prevent this in future, we can think of DENY (as follows), but we don't know the specific login. So, how to make sure no-one can do a full backup:

```
DENY BACKUP DATABASE TO [LoginName]
```