You will need to have separate running Snapshots for each task or day. If Snapshot is scheduled for the day that he deletes files then the Snapshot will perform its process for that volume and if the data is deleted then Snapshot will overwrite its existing data with the current and you will not be able to restore as the Snapshot will record the volume with the deleted data. You could remove the Snapshot from the Target Manager and when you need to restore just enable again, just as long as the Snapshot is not scheduled to run during the time the data was deleted.
thanks for your efforts to explain snapshots to me. I'll just have to play around with them to understand them to a level where I can implement a fool proof backup strategy.