Scripts

Okay, I don't know what your general knowledge of scripts is, so I'll try to explain it simply:

First, you need to assign script names to the desired units in the editor and configure them so that they are guaranteed to join the heroes of the player you want (the relevant items are highlighted in the screenshot).



Then, in the script, for convenience, create a table through which it will determine the presence of units on the map:

stacks = {'script_name_of_unit_1', 'script_name_of_unit_2'... and so on

Then, use a new day trigger to check daily for the existence of units:

function NewDay()
  if GetDate(DAY) == 'day when the check needs to be performed' then
  -- further check for the existence of units and transfer to the desired hero
    for i, stack in stacks do
      if IsObjectExists(stack) then
        MakeHeroInteractWithObject('Script_name_of_the_desired_hero', stack)
      end
    end
  end
end

Trigger(NEW_DAY_TRIGGER, 'NewDay')