grouping entities

I am looking for a way to group entities together so when they all pass through trigger, the trigger will fire. When only one
entity passes through, it doesn't fire. I have a filter_Activator_name
entity, and what I tried to do was name all the entities the same thing
(not 01, 02 etc. just all the same name) I am trying to make the
trigger unlock a button once 3 of my entities fire it, however it
always triggers after one has passed through. I should be able to put
one through and see that the button still does not work. I hope this
isn't terribly confusing. Thanks for the assistance.

Looks like filter_multi should do what you want.