^^^not as easy as you think,you got to live or work there for atleast few years, not sure how long it is , pay the tax for few years, professional degree grad than you have a CHANCE to get PR. or your parents stay there for more than 5 years than apply for PR the whole family. not as easy as you think, just think about how many student there are in Aussie, In my high school there's like 1/3 of the student all go to Aussie to study.

emm...may be your sis apply for gov job,or some job that really important to their community.or may be your sis proven to be a very good citizen.