How can I save just a-k named files?

Here is an example using Xcopy that you may convert to your robocopy

Open up a text editor and type in the commands. When done save as whatever.Bat. then just click on the bat file. You choose name for "whatever", but need the DOT bat extention.

E:\ = Drive E Root directory. I:\BU_E is where you want it back-uo to
In my example - copy every thing from drive E to Folder BU_E on drive I
For an explaination of the /x - open a dos window and type xcopy /?

xcopy E:\a*.* I:\BU_E /E /S /I /R /Y /D
xcopy E:\B*.* I:\BU_E /E /S /I /R /Y /D
xcopy E:\C*.* I:\BU_E /E /S /I /R /Y /D
ect