hi, by the sound of it,at the light with the two cables, put one of the reds (from the cable with two reds) and tape it up, then connect the other ed and black to the fitting, but obviously I am only assuming thsi sis how it has been wired, without actually testing it it hard to tell, i can only assume that the wire with two reds is the switch feed and return and the red/black wire at the first light is the live pair feeding them, please ensure you turn off at mains before doing this, (sorry to say the obvious,of course you would) if it goes off with a pop, please come back and let me know, but I think that is how it is wired, good luck, Ray