Thanks for all your input folks. Realitynotincluded, yes we're in WA unfortunately, but I'll pass on your message to my daughter's carer, Catriona - you never know it might help. TeeTMI, I have looked at the CSOL but there doesn't seem to be any job title close to "support worker" or "carer" or similar. We will take another look at it though. I note that you're a migration agent and would ask if you have a feel for the sponsorship approach in such a case as this. Catriona has seen an agent who wasn't much help, although whether this says more about the limited options available to her or the quality of the agent I'm not sure. For your information I have identified the Australian Community Workers Association (ACWA) as a possible source of advice.
Thanks again everyone. Brad.