Hello Petra,
I have an Iomega zip drive that's external. I got it specifically for
backing up my family file. The Iomega has a feature called Quick Sync that
allows me to choose what programs I want to back up. The Quick Sync can be
turned on & off, so if I'm checking a file someone sent me that I don't want
taking up space on the zip drive I just turn it off, then turn it back on
later when I'm working with my own file.
My boss has a zip drive (I don't know what kind) built into her computer &
she can also choose what programs she wants to back up on it. I would think
your zip drive would have something similar unless it's a very old one.
Check your owner's manual or the "read me" file, if there is one. Hopefully
you'll find an option for choosing what programs you want to back up.
I have FTM version 7.0 too, & for the longest time it drove me crazy trying
to figure out how to get my file to the zip drive. I was just looking in the
wrong place, which is normal for me. 
Hope this helps.
Gloria (Landwer) Scott