https://github.com/alexras/pylsdj
pylsdj is a arguably the most comprehensive library for dealing with LSDJ save files out there. It includes saving projects out of .sav files, loading them into other save files, loading and saving instruments between projects and editing things like tables, chains, phrases and the structure of the sequence itself.
This effort began way too many years ago, and had a few false starts along the way. It's finally to the point where it's documented and I'm confident with advertising its availability.
If you're not a programmer and some of these features sound exciting to you, Little Sound MC (https://github.com/alexras/lsmc) is coming soon to a computer near you (really soon, I promise; I just have to get it building on Windows).