I am using Atlas N scale (Atlas code 80) switch machines (undertable, 3 wire) I have three lines going into a coal mine. I would prefer not to have to hit multiple switch controller to open up the track for each line. Is there issues with me wiring it a way so that one push will control multiple machines. Can all the grounds be tied together and going to a single switch controler, leaving the other controler with out a ground. I see how I can do it, just wondering if there are any issues. What if you had 4 or 5 lines? Am I going to shorten the life of my switch machines?