Back up a drive to another drive's sub-folder.
 

Is it possible to backup a drive but have the backup not erase any other content in the destination drive, instead have SuperDuper place the backup in a sub-folder of the destination drive?

Using an image. See "Storing a backup alongside other files...", linked from page one of the User's Guide (Help > User's Guide).

Note, though: I don't recommend this. I suggest partitioning the drive and storing the backup directly on the drive. And, certainly, the files on that drive should be backed up somewhere, right?

Partitioning the drive sounds like the solution I needed. Thank you, appreciate it.