There is no easy way to do it. But try this:
Go to your catalog folder. The default location is C:\ProgramData\Adobe\Elements Organizer\Catalogs. You can also find the catalog folder listed by going to Help>Sys Info . . .
In the catalog folder, you will find a file named rmf.3.cache
Open this file in a text editor like Notepad
Replace whatever you find there with C:\Users\Martin\OneDrive\Pictures
Save the file with the same name. (Make sure that Notepad doesn't try to change the file extension to .txt
When Elements starts to search for a missing file, it should start the search in the OneDrive Pictures folder and will hopefully find it quickly.
Now, if you want to reconnect all of the missing files, try the following:
Click on File>Reconnect>All Missing Files
A dialog will appear with a list of the missing files
Select a file. It will show the original location. Hopefully, the OneDrive folder has kept the same structure.
Use the navigation tool to navigate to the new location.
The selected file should be displayed on the right side.
Click the Reconnect button. All of the files in the same folder should reconnect automatically.
You will probably need to do the same for each folder, but some may reconnect automatically.
Let me know if this works for you. There are some other techniques available that may make it easier for you.
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