There is no need to know where the files are, because when you launch a bat file the working directory is the directory where it was launched (the "master folder"), so if you have this structure:
.\mydocuments\folder\mybat.bat
.\mydocuments\folder\subfolder\file.txt
And the user starts the "mybat.bat", the working directory is ".\mydocuments\folder", so you only need to write the subfolder name in your script:
@Echo OFF
REM Do anything with ".\Subfolder\File1.txt"
PUSHD ".\Subfolder"
Type "File1.txt"
Pause&Exit
Anyway, the working directory is stored in the "%CD%" variable, and the directory where the bat was launched is stored on the argument 0. Then if you want to know the working directory on any computer you can do:
@Echo OFF
Echo Launch dir: "%~dp0"
Echo Current dir: "%CD%"
Pause&Exit