Quoted from frenchmarky:Meh, even with the ground wire off the bonus lights still flicker, apparently it's time to try some non-ghosting leds. Or maybe I could add one dropping resistor at the bonus unit where it then feeds into each bonus lamp so it's sort of like adding resistors to all ten bonus lamp sockets...
The ghosting current comes from the positive side, not your ground. You would have to put some sort of resistor on each wire to the socket to take care of the problem. That is taken care for you by an LED, so I do not see a real solution to the issue except an LED that is non ghosting. Just my 2 cents. 
