How to repack .bf files?

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I know someone made a post about this, but he didn't get the answer. Instead he got the answer to how to extract it, Now I need to know how to repack it because he didn't get his help and I want to make my own mod and i need to repack to a .bf, Here's information about it:
- .BF files are ubisoft files.
I just want to repack so if anyone has the answer, thanks.