lokking at the way this circuit is wired, i personnally would rewire both sets back to the distribution point (if the client want to bear the cost),
I have spoken to on of my work mates and he suggests that the above is the best way to do things and also you say you are changing the control gear (ballast) within the fittings,
this is a good idea, but you still havent let us know what type of HID the fittings are.
Having the lot drawing 50 amps is high, very high.
I wish i was closer as i would like to see the installation for myself.
keep us posted as to what happens.
John H
