It is my intention to included my MIL as a dependent on my 457 visa. She is most certainly financially and emotionally depedendent on my wife and I, but in the event that some grumpy so and so at Immigration doesn't see it that way, we will go the Parent Contributory visa route once we get PR.
However, as she IS dependent on us and we wouldn't go without her, I was thinking that she could perhaps apply for a 676 or similar visa, which could see her spending the better part of a year with us, then go back to South Africa for a few months to spend time with her son. She could then reapply for another 676 visa etc etc
It will take at least 2 and a half year for her PC visa to come through and I'm trying to ensure that she spends as much time with us as possible during this period. It will be expensive, but I don't see any other way around it. Any suggestions/advice?