External ssd help

I'm trying to add some roms (GCN, Wii, N64, & SNES) to my Wii u but my SD card is too small so I want to add them to my external ssd but I can't directly add them to it through my (windows) laptop because it requires multiple levels of reformatting so everything gets deleted. Is there a way to move files (and be able to play them) on console or even a way through my laptop that wouldn't make the console force a reformat?