I am using microsoft CAB-SDK(FCI, FDI library) to create a program to compress and decompress files. Everything is fine till I need to have a function to append new files to an existing cab file. I can't find a way to do that. I mean, it seems like FCIAddFile can only be called after FCICreate is called, and FCICreate will destroy the contents existig in the cab file. That's what I figured. However, I think there are many compressed/zip softwares which have the append function and I am wondering how do they make it if they are using the CAB-SDK as well. Any help will be appreciated.