It’s possible that we may be able to find a compromise that satisfies the “Let’s cram every villain in the land” and the “none of these characters would actually work with (or even know) each other” schools of thought:
What if the expansion is more or less just more Fantasyland, with individual IPs in charge of their individual ride/shop/restaurant. But the big Maleficent boat ride COULD involve a ‘summoning of sorcery’.
Maleficent all by herself is not that interesting. Maleficent with Capt. Hook, Cruella DeVille, Sir Hiss & Prince John, Gaston, Ratigan and Tomatoa is stupid.
BUT, a measured, thoughtful retcon that pulls together the wicked witches and sorcerers that all have the same vibe … maybe all study the same book of dark magic… that might work.
Again, this idea is for a single attraction where action commences, climaxes and ends, not for the whole land.