Non-Instructed Advocacy: Advocacy for People with PIMD

In Australia we often hear about self-advocacy in the context of people with disabilities standing up for their rights, and at times having support to ensure their voices are heard, but what happens when somebody does not have a voice? Advocacy systems often rely on an individual saying "I want an advocate to stand beside me on this issue". This directive may not be able to be made by people with PIMD. Sometimes it may be difficult to know even what a person's perspective on an issue is. Does this mean they do not "qualify" for advocacy?
In the UK, becoming increasingly popular is the concept of "non-instructed advocacy". The Oxfordshire Advocacy Development Group state that "Non-instructed advocacy is a form of advocacy that sets out to support those people who are not able to instruct an advocate or to say what they want for reasons of communication difficulties, lack of comprehension, severe learning disability or dementia" http://www.oadg.org.uk/noninstructed.asp. Rather than a person saying what they want, non-instructed advocacy relies on observation and knowing the person rather than being told. This presents a challenge to common forms of advocacy. It requires really getting to know a person over time, and then knowing how to represent the person without bringing in your own views or agenda, without clear confirmation from the person being represented.
Non-instructed advocacy is not simple, and controversy is attached to it. Lawton (2006) states that "some people argue that this cannot be true advocacy as the person has not asked for this support and this might be one reason for people with high support needs missing out" (p.14). People with PIMD are missing out on advocacy. The voice a person saying "I want to make a complaint" is listened to much more readily than somebody who's body language is saying "I am not happy with this". Are people with PIMD not to be listened to because they don't have a voice?
What is happening around Australia for people with PIMD in the area of advocacy? One example that I can think of is a small organisation whose Board of Management is made up by each resident and their voluntary advocates. The advocates have long-term relationships with these people, and on the Board of the organisation represent both themselves and the resident. Does anybody else know of initiatives that enable advocacy for people with PIMD?
There are few resources around on non-instructed advocacy that I have been able to find. One resource is Lawton, A. (2006). A voice of their own: A toolbox of ideas and information for non-instructed advocacy. Kidderminster: BILD. I claim no expertise in advocacy and would love to know more, particularly if this may be an avenue for improving the lives of people with PIMD.