You could simply solder four wires to your one thick feed wire, however I've never really got the hang of soldering myself and have given up with it now. If you've not tried soldering before I wouldn't recommend trying this route as its a ballache.
I would use a chocolate block connector like you'd use with your house wiring, and stick all the wires in one end and tighten the grub screw. It aint pretty but it works. No doubt someone will jump in and say that this could never possibly work for any length of time, but I've never had any problems with this method. Plus if your wires do pull out after a several thousand miles you just undo the grub screw, stick em back in again, and retighten, and good for another few thousand. Just because something is simple or scruffy doesn't mean it isn't effective.
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