I'm assuming an extra option in the lamp dialog for 'same time' floors that would allow you to leave NPCs there. For instance the current way would be changed to something like...
By picking to leave a NPC they would automatically be activated upon the player choosing to activate one.The Runic Lamp appears to need to be activated at the same time as all others on this floor.
-Activate Lamp
-Leave Lion at Lamp
-Leave Prishe at Lamp
-Leave Ulmia at Lamp
-Ignore Lamp
So far as orders go I think that one they just don't bother with changing. In either case I won't disagree that it does seem like it'd be difficult to do with what limited AI the Trust NPCs have.