Hey guys, I just worked out how to apply update nca files to original cartridge ncas. I'll use Kirby Star Allies as an example. I used XCI-Explorer to pull the largest .nca out of the games .xci file (which I named kirbystock.nca), and then had the update .nca (which was named kirbyupdate.nca) file too and used hactool to dump Section1 from them both, which gave me a romfs.bin with a file size of >3GB. So with hactool, your command would be something like hactool.exe -k keys.dat --titlekey=3676***8E3725A*****837AC6F1***303 --basenca="kirbystock.nca" --section1="atmosphere\titles\01007E3006DDA000\romfs.bin" --exefsdir="atmosphere\titles\01007E3006DDA000\exefs" "kirbyupdate.nca" I blanked out some of the update's title key, as i'm not sure if it's allowed to be posted here, but you can find it on Google i'm sure, or at least the way to find it yourself. So titlekey=(the title key that's used for the update.nca), you'll be then left with a folder ready to copy straight to your Switch, of course if your swapping it over another title, you need to edit the main.npdm to change the title ID.