Backing up additional WD Drives

I have two older WD’s (1 passport 1 my book) which did not come with backup software. If I do a backup of them onto my new  WD 2TB drive will the file changes on the older drives automatically update the backup of itself on the 2TB drive or will I have to manually update the backup.  Thanks.

If you use a software then it will be automatic

if no software then it will be manual…

If you are using Smartware that will depend if the old drive is supported for that task