I'm afraid until you can get some definitive answers about what paperwork exists, what money was paid to whom and under what circumstances, it's unlikely anyone can give you any meaningful answers or guidance.
Most of us ordinary people don't understand "the ins and outs of the whole process" of buying a house, which is why they employ the services people who do, solicitors, in order to protect their interests.
The worst case scenario here is that the money they paid the builder / developer is tied up in the liquidation or gone completely and they won't get their house either. I stress this is the worst case scenario as we have no real information.