One of the Rex charter flights is coming back to Sydney, this will most likely to be empty. The other will likely be used on a scheduled flight.
I cannot find any more charter flights from Broken Hill either today or tomorrow. Rex are the only airline that flies to Broken Hill to Sydney, Adelaide and Dubbo (another regional town).
Therefore, unless they go on one of the limited scheduled flights, I cannot see them using Broken Hill airport again, so maybe a long self drive in a car or a train to their next destination.