Possible to MOVE files?

[Lunix]

I want to move rather than copy files.

I use Macrium to backup my machine. But I use a USB connected drive as the primary repository, and the secondary one is a local SATA drive (D:) that is always connected. I want to back up that drive too, but I don't want to backup the other backups that were stored there when the USB HDD was not connected. I want those moved, using FFSync, to the USB HDD when it's connected; then I can back up my D: drive.

Thanks for your help. I am afraid that I already know the answer. But, I'm a newb so I hope to be proved wrong.