A PR holder or Citizen of Australia / Canada can sponsor his/her parents by applying PR visa for them. The time frame of this visa is usually long and lengthy depending upon the rules of the particular country. For Canada you can sponsor your Parents and Grand Parents which so popular these days as Canada choose 30k Parents each year from the whole lot. For Australia you can only sponsor your Parents, and because of the various complication people are less interested in it.
a letter of invitation from your child or grandchild who is a Canadian citizen or a permanent resident of Canada that includes:
proof that your child or grandchild’s household meets the minimum necessary income; examples include:
proof of payment for medical insurance from a Canadian insurance company that is: