Synchronization between external hard drive and network server

I am using the following:

Comodo Backup
Windows XP
Seagate FreeAgent portable hard drive

Seagate’s software does not allow a backup of network drives.

I am trying to copy the documents I access on a network server to my portablel hard drive for use at home. To do this I’ve set up a synchronization backup, with Comodo backup software, using the network drive as my source and the Seagate as my destination.

Assuming I use the portable hard drive at home to edit my documents, how do I “overwrite” the network version of my documents with the latest version? Right now, I think I’ve got to set up a Copy with deleting other than source folders backup. Is this correct?

Help! I really want to make this work and feel I must be awfully close.