Can I combine Time Machine backup drives?

I have several external hard drives that I have been using for Time Machine backups. I want to consolidate them into one.

I do not want to delete my old backups. I do not want to merge old backups either. Just want them all available as individual backups on a single drive.

Can I just drag-and-drop the backup file? If not, how can I put all the backups onto one hard drive?