I passed the whirlpools later by saving and reloading, with my entire army :-[ and there were no problems with killing the deans ))) although I could have just used magic to defeat them. In general, you don't even need to save and reload; just take a pack of goblins and you need 2 free slots - in one, put all the goblins, and after each whirlpool, detach one unit and do this with the entire army in all the other 5 slots.
In general, it doesn't quite work out as intended... and to make it work as intended, you can't do it with standard means (( you need an editor... here, take a look at my map; it has clear restrictions made with the editor (for example, the most important thing is the ban on losing any unit from the army, like in Bitter 17, there was such a game, where you also couldn't lose anyone), the map is based on Lord of the Rings http://phomm.narod.ru/homm3maps.htm