When merging and checking it, a lot of errors popped up, so it hasn't been fully tested (I didn't have time). But everything should work (heroes transfer with all their experience and spells).
Installation is simple: put it in the Maps folder (if it doesn't exist, create it), and in the game, find Modifications, and then it's even simpler. :) If any errors occur, please report them here.
Download in the header.