Hello, perhaps you could try creating a mod that includes all the creature stats from Might and Magic Heroes VII in Heroes of Might and Magic V.
1) In the game directory, open data.pak using WinRAR (or another archiver).
2) Copy the GameMechanics folder from it.
3) In the GameMechanics folder, delete all folders except Creatures.
4) Open the game/website with the stats and abilities of the creatures.
5) Enter the necessary stats and abilities for the desired creatures.
For balance, I recommend using the NOIADE program.
6) After all this, add the GameMechanics folder to the archive, change the extension to .h5u, and place it in UserMods.