How to do a Live distro with 3 partitions?

My case is: I have an external HD (in fact, an internal HD assembled on an external USB case), 320GB larger, where i want to install a Live together a 3rd NTFS/FAT32/exFAT/whatever Windows accessible partition (this way I can import games easily than connecting through SSH or all other messy solutions “officially supported”).

Problem: already tried to 1-) normally flash the ISO using Balena/Rufus/Win32 Disk Imager, do 1st boot to expand /storage partition, remodeling the disk geometry via own Lakka parted interface (using another live install on a 4GB pen drive) 2-) flash the ISO same as above, but remodeling disk geometry BEFORE expanding the /storage partition

    • those two attempts returns on a error message of “disk could not be initialized, blablablah, UUID= ~large number~” 3-) flash a pre-installed pre-built ISO (from the mentioned pen drive above - where I already have the system “setupped” with savestates, emu BIOSes’, etc.), then remodeling disk geometry
    • this attempt was ALMOST sucessfull: the disk starting itself gets no error, BUT the /storage remains locked at the original ~3GB size available from the pen drive (and even ext2fsck or other Lakka available console commands didn’t worked).

I’v tried, also, to find any Windows partitioning tool that handles ext4 partitions (u know: i’m running out of external devices to do it with a live GParted disk or something like), but all seems to be paid!

Someone can help? Tnx in advance!

UPDATE:

Seems that I did it last weekend, after using a lot of related partitioning commands - but from inside the Lakka installation itself running (instead of running from another OS to do the intended alterations, even being another Lakka setup). I only can suppose that the FileSystem wasn’t being updated by the “host” OSes.

Thread can be closed. Thx for the space, and sorry on bothering!

Bad news: it didn’t worked! Plus i’v downloaded GParted live and it simple doesn’t boot from USB thumbs, idk why…