Hi, i can't help with much, but we are in the same boat, we have been here for just a year & our visa has expired. we aren't about to be kicked out, but cant come & go now is our understanding until we get a return rsidents visa ( RRV ) . we have also been told, but don't know for sure, that you can't apply for a RRV until you have been here for 2 years !!? I also had the same worry as my parents are elderly & my Mum had been ill. happily she has recovered & is coming out to see us for Christmas so we are doing the other year & will hopefully get the RRV next year to visit her. Hope this helps ?
If you are in Australia and required a RRV, as long as you can show that you have ties to Australia, House, rental agreement, money in Bank, Job, Kids in School etc, and a reason why you needed to make the trip, you would likely be able to get the 3 month RRV if not eligible for 5 year one. Dont worry too much about it.