How do I merge my windows "(C:)>Users>User>Desktop" folder with my "Onedrive>desktop" folder?

How do I merge my windows "(C:)>Users>User>Desktop" folder with my "Onedrive>desktop"? 

I use 4 laptop and 1 desktop computer in various locations daily.  I have inadvertently found that my recently purchased new desktop, when I first set it up with my existing Onedrive my new computers' "Onedrive>desktop" folder and the "(C:)>Users>User>Desktop" folder were one and the same.  In addition, the same week, I reformatted the system SDD in one of the laptops and when I set it up with my existing Onedrive, it also was one and the same with the "(C:)>Users>User>desktop".  For these 2 machines, anything I put on my desktop on one machine ended on my desktop on the other machine.  But the 3 other machines, they just got the new item added to the file list in the "Onedrive>desktop" folder.  No change in the items appearing on the desktops.  So, how do I merge my windows "(C:)>Users>User>Desktop" folder with my "Onedrive>desktop" on my other 3 machines?  What am I missing?  Thank you for reading.