Speech and Language in Children with CP

Hello,

My 3 year old has hypotonic CP and I'm trying to get her speech and language services through the school. She just missed the cut off for qualifying. She has about 50% intelligibility, a tongue thrust, lateral lisp, low jaw tone, and she's struggeling to form her sentences. Basically her speech is very slushy.

The school doesn't care about any of the above. They only care that the specific letter sounds were age appropriate.

How can I prove that early intervention is crucial for her speech and language development due to all her issues? The school is known for over prompting and passing through kids so they don't have to provide services.

Anything information you can give would be greatly appreciated.

Thanks,
Danielle