Children can be sponsored by their parents as long as they are under 22 years of age, and are not married or living in a de facto relationship.
Children with disabilities can be sponsored, regardless of their age, if it can be proven that they have been dependent on their parents since before their 22nd birthday and that they are financially unable to support themselves precisely because of their physical or mental disability.
To sponsor children it is not necessary to demonstrate that you have a specific minimum annual income, unless the child has a child.