How Can I Speed Up Insurance Claim Processing?

My family and I are trying to find an appropriate residential treatment facility for my sister (who suffers from bipolar disorder and substance abuse).

One of the facilities we spoke with accepts insurance but informed us that since this can be considered a “pre-existing condition” and her insurance is relatively new (her husband recently switched jobs), there’s an extended waiting process of possibly 6 months.

Is there anything we can do to speed up the claim processing? Insurance provider is bluecross of ca.