Separation and shared care with an autistic child

Hi there,

Does anyone have, or know of any resources for research around suitable shared care for autistic children.

Our Child's guardian has some pretty... contradictory and bizarre views and I'd like some weight behind supporting what is best for little one. Child is 8.5. Guardian has only met child once and has very limited understanding of Autism and ND matters, but has some very strongly held cliched beliefs. 

Notably...

Child has very clear wishes and feelings and has expressed frustration that these are not going to be followed. Obviously Guardians line is that due to child's age wishes and feelings are limited consideration which is fair to an extent. She is also making the case that wishes and feelings should have lesser weighting because of the autism. I have seen some studies that suggest actually for child's mental health autistic children's wishes and feelings should have greater priority. Child is very high functioning and academically performing at the equivalent of a 14/15 year old. EQ is potentially lagging, although this isn't confirmed. 

Guardian has adopted an approach of frequent 'smaller' changes to living arrangements (smaller including changes in overnights etc. The result is that little one hasn't had a consistent pattern now for over 2 years. The advice we've had from psychologists is that this seems very unusual and counter-intuitive.

Finally advice we've had from psychologist is that arrangements should be consistent and routine. Guardian has interpreted that as meaning she must stay in one home.

Clearly none of this is in the best interests of little one's wellbeing and so I'm looking for any advice in terms of academic studies, case law, examples of shared care working well for autistic children, etc. and potentially if anyone is aware of anyone that can provide subject matter expertise or advocacy. 

Thank You