Differential Backup on Different Location to Full Backup Possible with CB?

I am just trying out CB and would like to do the following:

  1. Do a large full backup to DVD’s to take offsite once, say at start of month
  2. Perform a small differential backup each night online (minimising the transfers online)

The reason for this is that the daily backups can be automated with no need to take disks offsite and disks would only need to be taken offsite once monthly. Doing a full backup online is not feasible however due to limited bandwidth here.

I have tried to do this, however, everything I try means that the first differential backup tries to write an entirely new full backup. This will not work for me as a full backup will never complete to online storage due to the limited bandwidth. It seems that CB tries to use a single file (I am using CBU type) for all the differential backups - is it possible to change this behaviour?

Could someone please advise how I could use CB to do a backup system like I have aforementioned? Or will I have to use a different backup system?