In the time it took me to write my post, and chase a 2 year old around, I see that someone else mentioned the Family Consultant. I'm sorry to hear that yours in not being more assertive. We are on our 2nd FC (the first one moved on to other pastures) and there is a great deal of variation on how they are willing to work with the schools. Maybe you can ask explicitly for a letter to your child's school? Perhaps if they receive a letter addressing how rarely these kids come along and what their needs are, then your school will agree to the stepwise approach that our wise Grinity has suggested.
Actually, (reading your latest post) our second school gave the new grade acceleration (from 7th to 8th) after we paid for the Woodcock-Johnson achievement test. Schools don't seem to know what to do with IQ tests so much as seeing where they are academically. Maybe that is what your FC is hinting at?
Do you have recent achievement testing? (see that danger of not reading all of the posts!!)