ON backup with onevm disk-saveas

Good day.
i have a little problem.

I use KVM+ON/
I try to make backup with the help of ON.
onevm disk-saveas vm_id disk_id backup_name
This file saves in the same datastore as VM. Using cp i migrate it to the mounted NAS and after delete original file.
So, i have question. How i can restore vm from this file? As i understand, i should add it to the images again, but i dont undersand how.
Thank you for ypur help