Improving chances of obtaining Visitor Visa (Family stream) for more than 3 months

Question

My sister has applied for a Australian Visitor Visa (family sponsored stream) and I, an Australian citizen, am the sponsor. She has a plan of spending 6 months traveling in Australia, of which 3 months will be used for an English language course (the visitor visa allows study up to 3 months).

However, the case officer has indicated, due to applicant profile and information provided, they will be satisfied to grant her 3 months instead of the 6 months requested.

I would like to know what kind of extra information would typically help make a case for her being able to be granted six months. I'm assuming the case officer decision is not final yet. Information we already provided included:

• My capacity of paying a bond;
• Information that the applicant is taking a leave from her job in her home country and will still have the job when she comes back;
• Financial data showing enough savings to travel, including pre-paid tickets and study fees.

Answer 1

I have ultimately called the Department of Immigration and Border protection to seek advice on how to obtain a 6 month visa as originally requested.

I was told that under the Visitor Visa (Family stream), it is customary for the department to grant 3 months to siblings, while 6 and 12 months are only given to parents.

Counter-intuitively, I was also told she would more likely get more than 3 months by applying independently. Also, she being for a country deemed to be low-risk (although it's not an ETA country), they have informed there was no need for sponsorship.

Finally, a 6 months visa was granted under a regular visitor visa.