How to do I make it so something only happens when the player isn't in the los of all npcs

Hello I'm currently working on this 3D game in construct 3 and I in it there's a family called npcs that you can talk to.

with that feature I have a section that detects if the player isn't in the los of the npcs it will set the dialogue text to "" but with that a i've discovered that if even one npc isn't in the los it with still make the dialogue text "" is there anyway to fix this?

game file: 1drv.ms/u/s!AhNaCCeFIGIhkCb2boyRqGvZ_seI

(sorry for the long winded explanation)

You can just use an Else. If NPCs have LOS, Else set text to "". The Else triggers when nothing has LOS. Also please remove the trigger once conditions. For the typewriter logic you'll have to move it somewhere else to trigger once, separate logic required such as switching a variable to true or false on the specific NPC.