Prospective Marriage Visa
"The Prospective Marriage visa is for people who want to come to Australia to marry their prospective spouse.
If you plan to marry in Australia, you must complete a “Notice of Intended Marriage” form and give it to the celebrant who will perform the wedding ceremony. You must also provide evidence that you will marry your prospective spouse within nine months of being granted the visa (such as a letter from the celebrant who will officiate at the wedding)."
- taken from
I can help you with all this documentation, I am aware of exactly what ou will need to satisfy this criteria.
I have assisted and married many couples who have gone through this process.