Oh the old dreaded three wire 4 terminals at least it is better than the 4 or more wires three terminals.
You will not find qualified people giving you advise as you must be qualified to do this type of work anywhere in Australia. I'm sure you could get this information at the Google university. Most electricians if they knew you would give you this advise so you could do it yourself but as this is a public forum I will have to decline to answer.