This is a really simple way to do it:
*** IF ***
TRUE
*** THEN ***
(Object list) 'Porter': Add 'Elven Porter'
(Object list) 'Porter': Add 'Men Porter'
(Object list) 'Porter': Add 'Dwarven Porter'
(Object list) 'Porter': Add 'Wild Porter'
(Object list) 'Porter': Add 'Mordor Porter'
(Object list) 'Porter': Add 'Angmar Porter'
(Object list) 'Porter': Add 'Isengard Porter'
Then this as another script which is below this first script (so it is read afterward) or part of the first script - just make sure the porters are on the list before referencing them.
*** IF ***
TRUE
*** THEN ***
Find unnamed unit 'Porter' on team 'Team/Player_1' owned by player 'Player_1' and set reference UnitRef'Porter1'
Unit 'Porter1' is removed from the map
Find unnamed unit 'Porter' on team 'Team/Player_2' owned by player 'Player_2' and set reference UnitRef'Porter2'
Unit 'Porter2' is removed from the map
You will find the object lists in Scripting>Object List>Add unit to object list (or something similar)
You will find the referencing script in Scripting>Reference>Find nearest unit .... [461] (or something similar - it is the last in the reference folder)
You will find the delete script in Unit_Other>Damage or remove>Remove unit from map (again perhaps something similar)
I say 'perhaps something similar' because I haven't gone and checked it but I'm sure this is adequate enough direction.
This will work for RotWK worldbuilders, perhaps BFMEII, perhaps not.