Filter unwanted unit with trigger condition

[TheDestroyer]

I need a condition that works where a trigger will not run if the picked unit is involved in another trigger. Is this possible?

 

[Pharaoh_]

Add it in a unit group which will be used only by that trigger and check if the unit is inside the group (boolean comparison, Unit - Unit is in Group).

 

[Bribe]

What other trigger? What are you even talking about?
You need to give us a little better background details
than this.