Hi man,
I dont think you can ,
If you want different actor to use the same material instance, they have to share the same features.
If you want different colors, or different parameters , you need to have different instance of the material. (pretty completely sure)
Get all actor of class, is a node to get a list of all the actor of a type, in the level,
With that you can have a list of your “Doors” , to use as reference to call a command to every door, or to evaluate which door shoud do the actions.
But it dont help you in any way with the “material instance problem”
Another dirty way could be using the mesh
for example add a mesh to hide the emissive mesh,
And let every actor animate the “Hider mesh” to show or not show the emissive mesh .
This will leve you with only 1 material, and 1 blueprint, but i dont know about performance XD