REM Command Line Version
for %%I in (*.rar) do "C:\Program Files\WinRAR\RAR.exe" a "%%I" filename
pause
To create the batch file, copy the text above into Notepad and save it as "addfiles.bat", (without quotes). addfiles. Put addfiles.bat in the same folder as the RAR files.
replace filename with the file name you want to add
rar files need to be all in the same folder with the file you want to add