Uldics:
I think you want to use "foreach units thislist" to allow any unit (that meets your other conditional criteria) that is in the trigger area to be included in the array of units that will be affected by your script. As I am not really a scripter, I am not sure how to incorporate this into your condition. Usually it is used like this:
"_x setdammage 1" foreach units thislist
Try something like this:
Make a trigger that will cover all of the units that you want the eventhandler applied to and add this:
West present
Condition this
then add this to the OnActiv field:
sfzHandler = [_x addEventHandler ["hit",{_this exec "spawnkill.sqs"}]] foreach units thislist
If the above does not work,perhaps you can use a different trigger to make an array of all the players that need the eventhandler then use that array to add the eventhandler to the units like so:
Name - Arraytrigger
West Present
On Actv - west_liveunits = thislist
Then make a trigger that covers the entire island (or you may be able to put this in your init.sqs) and put this in the OnActiv field:
sfzHandler = [_x addEventHandler ["hit",{_this exec "spawnkill.sqs"}]] foreach west_liveunits
Let me stress that I have very little scripting knowledge but I am a fairly quick learner. You more than likely have far more knowledge than myself so you may see that some of this could be garbage. One other thing that stands out is your use of _this. You may need to change that to _x for my (or your earlier) method to work. As usual, I am posting from work so check all syntax and commands (especially my use of (),[],{} and ""). If you are lucky, maybe CD or GB will see your post and give you a definite answer. I gave this one a shot as I hate to see questions go unanswered.
Wadmann