Best way to book Classic Reward with layover Sydney to Dubai to Athens using Qantas points?

Hi, thanks for the great website you are all so helpful.
I am looking to book Sydney to Dubai then Athens in business class with QFF points but rather than only stopping in Dubai for 3 or 4 hours I would rather stop overnight and get the next day flight (less than 24 hours) I can’t work out how to do that on line thru the Qantas website. If I make it 2 separate flights it costs more points?

Use the multicity tool