[Cesar82]

@BLACKFIRE69, Thank you very much for the updates.
Maybe you can include an additional function...
function FXPckrAddFileList(const FileList: WideString): Boolean;

Usage like this:

StrList := TStringList.Create;
try
    StrList.LoadFromFile(ExpandConatant('{src}\FileList.txt'));
    FXPckrAddFileList(StrList.Text);
finally
   StrList.Free;
end;

You could also store files with a folder structure inside Data.dat.
To do this, use the character "|" as an option to inform the destination path in the internal structure of Data.dat. If "|" does not exist, add as a file without a subfolder in the internal structure of the items.

FXPckrAddFile('C:\my_test\filetest.txt|my_test\file_name.txt');

This would allow using files with the same names for different cases.
Thanks!