change file title without changing files

[closelate]

Hi there,
I want to display different file titles in merge view, but not the file content. Where do I modify the code?
For example: I want to merge file1.txt and file2.txt, but when display the tile of the file1.txt, I want change to A.txt, same as file2.txt to B.txt
Hoe do I do that?
Thanks