Yeah anything is possible. You could easily put a switch with jumpers over to the smoke unit. But then it would run all the time.

The other thing you could do is test the switch on the large board to make sure that it is letting power through it. I would do that before going through the trouble of making a whole seperate circuit for the smoke unit. I will admit though if HL had made thesmoke, motors, sound and other functions on seperate boards things would be easier for us to re-engineer and make better. f you need seomthing else let us know.