[LVL ED] Tips for lighting

[The chaser]

Well, I'm in need of help. There is a stove with a bonfire inside. When the bonfire is lit, a spot light gets activated. If the stove is closed, the spotlight will cast the shadows from the stove "door". But, I want this stove to create billboards. I've connected the desired billboards to the spotlight, but when I lit the bonfire the billboards do nothing (they stay invisible).

What should I do? Realism is very important, and the place where the stove is placed is a place with dust.