I would use variables that are set to true with the activation of each trigger the for the end trigger you would use the condition field and specify that all prior variables are true before activating the last trigger. Something like this:
Name - Trigger1
West (or whatever) Present
Activation - Obj1=true
Name - Trigger2
West (or whatever) Present
Activation - Obj2=true
...and so on for the triggers over objects.
Then for the final trigger:
West (or whatever) Present Group this trigger to the player w/F2
Cond - this and obj1 and obj2 and ...
Act - Whatever
As usual, this is posted from work so check my commands and syntax but this should get you going in the right direction.
Wadmann