Copying files from similar multiple folders into each of their child folders - robocopy

Question

I would like to use a batch file to copy files in a folder to a backup folder (OLD) within, on a Windows server. And I want to do this for multiple folders.
So for example, I have multiple folders, named like this:
C:\A01
C:\A02
C:\A03
...
C:\A50
I will nickname them here as A##.
Each folder has hundreds of files.
Then each year before updating them, I copy those files into a backup folder called OLD, for each A##, so I have a backup of last year's files. Then I copy in new files into C:\A##, in another manual process, individually.
So there will be folders like:
C:\A01\OLD
C:\A02\OLD
C:\A03\OLD
...
C:\A50\OLD
When I do the copy, to the OLD folder, I keep the most recent version of each file. But then the files that I later manually copy in will overwrite in the C:\A## folder and be this year's files, while C:\A##\OLD will contain last year's files.
How can I script this so it will copy all the files for each C:\A## folder into their respective \OLD folder?
I assume I would use a variable for the path I want to copy from and to.
I could use Robocopy or Xcopy.

Answer 1

in a script file
#echo off
cd c:\
for /f "usebackq delims=:" %%a IN (`dir /AD /B ^| FINDSTR /I /R "A[0-9]*"`) DO (
#mkdir "%%a\OLD"
xcopy "%%a\*.*" "%%a\OLD\" /ECIFHRY /D
)
it copy only the updated files (/D) to the OLD subfolder.
if you want to mantain ACLs of the files, use /ECIFHRKOXY
I suggest you to test it in a test folder, that you can generate with this commands directly in the shell
#mkdir c:\test76
cd c:\test76
For /L %a IN (1,1,10) DO #mkdir A%a && echo "the quick brown fox jumps over the lazy dog">A%a\file.txt