http://www.immi.gov.au/skills/skillselect/index/including-family-members/
Other dependent relatives
A dependent relative (other than a dependent child) can be included in your visa application when you lodge your application.
You cannot add a dependent relative to a points tested skilled visa after you lodge your application.
To include your other dependent relative(s) in your application, there are requirements and evidence that must be provided to prove dependency.
To be considered a dependent relative you must prove they:
have no other relative able to care for them in their own country
are not currently married, engaged or in a de facto relationship
usually are a resident in your household
depend on you for financial support for their basic needs and you have supported them for a substantial period
depend on you more than any other person or source.
Acceptable forms of proof include:
a certified copy of their birth certificate and proof of their relationship to you
proof that the relative lives in your household
proof that your relative has been dependent on you for at least the last 12 months.
if your relative is divorced, legally separated or widowed, you must provide certified copies of supporting evidence, such as:
the document of legal divorce
the document of legal separation
the death certificate of the deceased partner.