I don't know if there was any written agreement. I think if there were then the media would have been reporting it and their claim would have been almost an open and shut one. I guess they are relying on bank transactions being around the same time as mortgage transactions, etc, to argue their case. Hard to say.
The G's did and do not have any paper, signed or otherwise to the effect of Melissa agreeing to use their 1 million as a deposit on the apartment. It is precisely because there is no written narrative that supports the G's claim that this whole apparatus, this convoluted intricate back and forth, the class action, the designated receivership ( there has been , so far, two of those, both very expensive undertakings, neither of which was able to ascertain the probity of the G's claims. ) ... so it is not so much a matter of 'hard to say' but more a matter of ' easy to confirm' that had there been any paperwork at all, the ATO, the Receiverships ( 1 and 2 ) would have been presented with them by the G's.
But no. Their entire claim rests on their say so. Which, really, is not going to cut it, at least not without a series of expensive appeals. It is comforting to think that Melissa took care of her parents stability in keeping that apartment out of the scamming shindigs, but she was that mean. She had the money to pay out the mortgage and make their ownership free and clear of all burdens, but no. Not Melissa. Hence, her old mum and dad face the future in a Housing Commission flat in Campbelltown. Along with the brother, too. One day a rooster, next day a feather duster. Happens a lot.
I do think , come the judgement, there will be a certain element of 'culpability' assigned to all the claimants, in so far as they chose to invest with Melissa and not with a certified , registered investment organisation. In other words, they went for the high return, seemingly oblivious to the higher degree of risk. They did not do due diligence with their own money. The judge may see it all as a horse betting affair where people bet on the form and then complain when their horse runs dead last.
But one thing is clear, the G's have no firmer claim than anyone else involved, except they may be judged to have had slightly MORE culpability in their own demise , so to speak, due to their family connection.