Merge folders with similar prefix in filename

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I've spent all week trying to figure this one out with no luck. Originally tried to this as a batch script, then someone suggested WinMerge.
My goal is to merge folders and their contents together if they have a similar 5 digit code within the folder name. (and automatically/daily if possible)
This is an example of what I'm working with:

----[] Submitted Forms
--------> [] 45678 Lastname - Form A
-------------> 45678 Lastname - Form A.PDF
--------> [] 45678 Lastname - Form B
-------------> 45678 Lastname - Form B.PDF
--------> [] 11111 Lastname - Form A
-------------> 11111 Lastname - Form A.PDF
--------> [] 11111 Lastname - Form B
-------------> 11111 Lastname - Form B.PDF

The ideal output would look like this:

----[] Submitted Forms
--------> [] 45678 Lastname
-------------> 45678 Lastname - Form A.PDF
-------------> 45678 Lastname - Form B.PDF
--------> [] 11111 Lastname
-------------> 11111 Lastname - Form A.PDF
-------------> 11111 Lastname - Form B.PDF

Any ideas?