Backing up with new computer

So I used to back up with my previous PC via wifi. Now that I have a new PC, I want to back up again. But it backs up as a separate PC

What I want to know is how to merge the backups so I dont double what I’m backing up (including the backup copies)

Sorry, it’s been a long time since I set it up so I can’t really remember how to use it. Also Im using WD Smartware to backup, if there is a better program to use, please do let me know. Thank you
EDIT: I figured out how to change the folder location, but I still dont know how to merge the backups

Have you tried using Windows “File History” you can set which folders you want to backup and it just runs continuously in the background. It works great for my needs.