MagesPack DiskSpan integration?

[Masquerade]

^^
QuickBMS cannot repack a file traditionally, it's not that kind of tool. Reimport mode can work but it gets messy very quickly as you need to import empty files into the original archive and then reimport your files during installation. Many archive repackaging tools for games are game engine specfic or even game specific.

As for Steins;Gate, since the archives aren't compressed, you don't need to extract them. If you unpack the raw data, you can simply concatenate that data using bincat and then use xdelta or hdiffz to restore the missing archive information.