I am thinking about editing the Jazz 2 levels to make them more difficult.
I am going to throw in many more enemies and obstacles in the environment.
Would this be illegal seeing as I am modifying the original levels?

And I do not want to create new ones yet, I want to fix Jazz 2 as in my eyes the VERY low difficulty level kinda breaks it.
I'm not going to drastically change the levels, they will be almost identical - only more difficult.

If this is legal, could perhaps someone else do this as well? We could divide the levels between us perhaps? It's a lot of work